Season 27 superfinal games 21-30

After 30 games Stockfish leads 8-3 with 19 draws. Leela won a game pair and reduced the gap to 2 wins. Then Stockfish won 3 game pairs in a row and extended its lead to 5. It is still early in the match but Leela needs to improve its results to close this gap. It is interesting to note that after 15 game pairs there were 4 double draws and 11 decisive pairs. No pair had two wins, one for each side, which is quite unusual considering that the chosen book openings are biased enough for one of the engines to find a win in 11/15 pairs so far.

Games 21-22 started with a sideline of the Queen's Indian defense, Fianchetto, Nimzowitch attack. In game 21 Leela gave a pawn and opened the center, after a bishop exchange it moved the queen to d6 blocking the black d pawn. The engines agreed on their PV, Stockfish thought long on two moves and its eval started to increase, Leela's eval stayed stable. The black a pawn became a passer, the engines exchanged queens and the remaining bishops and Leela regained the pawn.

The white rooks were more active and the b6 pawn was weak. Leela's eval started to increase, the engines exchanged a pair of knights, then Leela captured the b6 pawn and exchanged a pair of rooks. Stockfish moved a rook forward and managed to capture the white b pawn and equalized material.

Leela attacked the black pawns on the king side with its knight. Stockfish lost only one pawn there but had to abandon its queen side pawn as well. The game ended in a tablebase win.

In game 22 the engines repeated game 21 for 12 plys. The continuation was similar, Stockfish placed the queen on d6 as before, but there were small differences in the location of the other pieces. Stockfish was a pawn down, its queen left d6 and the engines exchanged pieces. Evals came down, Stockfish tried to attack the black king but wasn't strong enough. It managed to regain the pawn, the game reached a double rook ending and was adjudicated. Leela wins the game pair, Stockfish leads 5-3.

Games 23-24 started with an 18-ply line in the Czech Benoni defense. The center was locked and all pieces and pawns were on the board. In game 23 Stockfish thought for 45 minutes on its first move, the engines followed Stockfish's PV and evals drifted down. There was a pawn exchange and a bishop exchange on the king side, for a few moves Leela's eval was close to 1.5 but it came back down after another minor piece exchange. Leela created a passer in the center, Stockfish gave a rook for a knight and captured the passer. The game reached a RR vs RN position and was adjudicated after Leela lowered its eval for the draw rule.

In game 24 Leela thought long on its first move, only 20 minutes this time and it played the same move as Stockfish in game 23. On its next move Leela did not follow game 23, Stockfish's eval started to increase. Stockfish pushed pawns on the king side, trying to open files and attack.

Leela's eval came down for a few moves, there were a few exchanges and Stockfish gave a pawn in the center. Leela's eval jumped back up after 7 moves, Stockfish regained the pawn and opened the f file. Then after a long series of exchanges the game reached a N vs B position.

Leela captured a pawn on the queen side but it took time to create a passer, while Stockfish had a pawn majority on the king side. Stockfish captured the black h pawn with its knight, the engines exchanged minor pieces and both queened a passer. Then Stockfish queened a second passer and mated. Stockfish wins the game pair, it leads 6-3.

Games 25-26 started with a rare sideline in the Queen's Indian accelerated variation. In game 25 the engines followed a long PV agreement, Leela's eval increased to around 1.5 and Stockfish's eval stayed around 1. The engines exchanged minor pieces, Stockfish's eval jumped on move 14 and then came back down immediately, still in PV agreement. After a pawn exchange Stockfish went a pawn up and Leela castled long. In a series of exchanges the engines reduced to a RBN vs RR position with black two pawns up. Only after exchanging a pair of rooks and capturing a pawn Leela's eval started to come down, but it remained too high for the draw rule for a long time. The game was adjudicated on move 100.

In game 26 Leela chose to not exchange its LS bishop, allowing Stockfish to block the long LS diagonal with pawns. There were no exchanges after the start, the engines locked the center, on move 24 there was a first pawn exchange on the queen side. Evals increased as the engines shuffled for a while, on move 33 a pawn exchange opened the h file and the engines exchanged a pair of rooks.

Evals slowly increased as the engines shuffled, Stockfish moved its major pieces to the king side and on move 52 exchanged a pair of pawns there. After another shuffle Stockfish exchanged pawns on the queen side, opened files and moved the rook forward. The engines exchanged rooks and Stockfish captured a pawn, then it captured two more pawns and a series of exchanges reduced to a knight ending. 

Stockfish pushed the center pawns forward, queened and mated. Stockfish wins the game pair, it leads 7-3.

Games 27-28 started with a rare sideline of the Scandinavian defense, modern variation, with white a pawn up. In game 27 Leela captured a second pawn, opened the e file and moved the queen forward. Stockfish forced the white king to move without castling and castled its own king. Leela captured a bishop, Stockfish used the exposed white king to capture the white queen for a rook. The game reached a RNN vs Q position with black a pawn up. Stockfish's eval came down, Leela took a long time to lower its eval. The game was adjudicated on move 130.

In game 28 Leela pushed e5 and expected Stockfish to take en passant and move the white queen forward as in game 27. However Stockfish waited, pushed pawns on the king side and exchanged the pawn on e5. The e file opened but the white queen stayed behind, both engines castled. Stockfish's eval slowly increased, Leela's eval stayed around and under 1. The engines exchanged queens and Stockfish created a passer in the center.

Leela's eval started to increase as well, the engines exchanged minor pieces and Stockfish pushed the passer to d6. Stockfish gave a pawn and offered a rook exchange which Leela avoided. The passer arrived to d7 safely and Leela blocked with a rook. Stockfish moved a rook to the 7th rank, Leela captured a pawn and the game reached a RRN vs RRN position, Stockfish saw the win in its PV.

Stockfish captured the black a pawn and captured a rook for a knight. Leela lost the second rook for the passer and the game ended in a tablebase win. Stockfish wins the game pair, it leads 8-3.

Games 29-30 started with a sideline of the Sicilian, Nimzowitch-Rossolimo attack, the black queen moved forward on the queen side. In game 29 the engines exchanged pawns and knights in the center and then the queens were off. Stockfish's eval came down, it gave a pawn and Leela created a passer on the queen side. The game reached a RRB vs RRB position, Leela captured a second pawn yet its eval also came down. Stockfish captured the white passer and Leela captured a pawn and created a passer on the king side. Stockifsh managed to get one pawn back, Leela found no way to improve and the engines shuffled. On move 83 Stockfish captured another pawn, the game was adjudicated on move 103 after exchanging a pair of rooks. In game 30 Leela drove the white queen away and avoided an early queen exchange. The black king moved without castling, Leela captured a pawn and now Stockfish avoided exchanging queens. Stockfish regained the pawn, its queen moved forward and cleared the black queen side pawns. Leela captured a pawn back but Stockfish was still two pawns up with passers on the queen side, yet evals continued to come down. The black rooks kept an eye on the white passers, the engines exchanged a pair of rooks and that doubled the passers. Leela got a pawn back, the game reached a RB vs RB position and was adjudicated despite Stockfish being two pawns up again. 

Season 27 superfinal games 11-20

After 20 games Stockfish leads 5-2 with 13 draws. Leela won a game pair, where in game 12 Stockfish only drew and the game ended in fortress almost identical to the one in game 8. Stockfish immediately won a game pair, then there were two double draws. In game 19 Leela couldn't find a win despite having a high eval. Stockfish won the reverse to increase the gap to 3 wins. So far the match is closer that what was expected after the premier division.

Games 11-12 started with a 20-ply sideline in the French Winawer, advance variation. In game 11 there were a few pawn and minor piece exchanges in the center and Stockfish went a pawn up. The black king moved without castling, Stockfish pushed the d pawn forward and created a passer. Evals were stable above 1, the black king side rook moved forward and offered it for a bishop (LS) but Leela didn't take. Leela regained the pawn and its eval started to increase. Leela then captured the black passer and Stockfish's eval also started to increase.

The engines played out a very long PV agreement and evals continued to increase. Stockfish gave the king side rook for the other (DS) bishop and regained the pawn. Stockfish captured another pawn while Leela moved a rook to the back rank through the open d file. Leela captured a pawn and exchanged a pair of rooks. The game reached a QRB vs QBN position and the engines cleared the queen side pawns.

Leela's progress was slow, it pushed the h pawn and it became a passer. Then Leela exchanged queens and moved the rook to the 7th rank. The white king moved forward and Leela created another passer, Stockfish lost more material and was mated.

In game 12 after the initial exchanges in the center Leela was up a pawn as before, this time the engines played out a long PV agreement that involved a RN for Q trade. Stockfish's eval started to increase but dropped back in the middle of the PV agreement, what did it see? Leela moved a rook to h7 to protect the g7 pawn, an awkward square for the rook. However, Leela just played waiting moves and Stockfish couldn't find a way to improve. It forced Leela to move the g pawn to avoid mate, but nothing else. After a long shuffle Stockfish pushed pawns on the king side and its eval increased for a few moves but then came back down. It opened the g file and exchanged a pair of rooks, the game reached a Q vs R position and ended in a fortress almost identical to the one in game 8. Leela wins the game pair, Stockfish leads 3-2.

Games 13-14 started with a 24-ply sideline of the KID orthodox varation played in high level human chess. In game 13 Leela pushed pawns on the queen side, the engines exchanged a pair of pawns on the king side. For a few moves Leela's eval increased a little, then came back down. Stockifsh opened the g file and threatened the white king, the first piece exchange was on move 34. Leela had a bishop pair advantage but evals came down. After exchanging queens Stockfish captured two pawns, then traded a rook for one of the bishops. The game was adjudicated 10 moves later.

In game 14 the engines repeated the first 13 plys of game 13. Leela moved its queen forward on the king side, too soon perhaps, and evals started to increase. Stockfish exchanged pawns on the queen side, opening files there. On move 35 the first minor pieces were exchanged, both engines had a passer on the queen side but Stockfish's passer was on d6 supported by major pieces. 

Leela blocked the white passer and protected its own with knights, it didn't try to attack the white pawn. The engines exchanged pieces until the game reached a RB vs RN position. Stockfish saw a win in its PV.

Leela lost the knight for the white passer, Stockfish captured the black passer and the game ended in a tablebase win. Stockfish wins the game pair, it leads 4-2.

Games 15-16 started with a sideline of the Old Indian defense, Tartakower variation. In game 15 the engines exchanged minor pieces and castled in opposite directions. The c file was opened and the engines exchanged a pair of rooks. Stockfish pushed pawns on the queen side and captured a pawn on the king side, creating a passer. The engines played out a long PV, exchanging the remaining rooks and more pieces and pawns. The game reached a BN vs NN position with white a pawn up, Stockifsh's eval was 0 and Leela lowered its eval slowly. Leela blocked the black passer on the 2nd rank, the game was adjudicated on move 86. In game 16 there were only a few exchanges after the start, a minor piece exchange and a pawn exchange in the center. Both engines castled short and developed pieces behind their pawn lines, on move 25 a pawn exchange opened the a file. Leela's eval came down, it moved a rook forward and exchanged a pair of rooks. Stockfish created a passer on the queen side and pushed it to the 7th rank, its eval also came down. The game reached a RBB vs RBN position and Leela captured the passer. There were too many pieces for the draw rule and the game ended in repetition.

Games 17-18 started with a 22-ply line in the Sicilian Dragon, Yugoslav attack, popular in high level human chess. There was one pawn exchange and all pieces were on the board, the engines castled in opposite directions. In game 17 the engines quickly left theory, there was a minor piece exchange on the queen side and Leela pushed pawns on the king side. In a series of exchanges the d file was opened and a pair of rooks was exchanged, Leela went a pawn up but evals came down. The game reached a RB vs RB position, Stockfish regained the pawn and the game was adjudicated. In game 18 the engines also left theory and exchanged queens early, there were no pawn exchanges after the start and the engines slowly exchanged minor pieces. The first pawn exchange opened the g file on move 36, the game reached a RRB vs RRN position and evals came down. After exchanging a pair of rooks the game was adjudicated.

Games 19-20 started with the Modern defense, Averbach system. In game 19 the engines locked the center and opened the c file. Evals increased steadily, a few minor pieces were exchanged. Leela pushed pawns on the king side and doubled rooks on the c file. The kind side was also locked and all pieces moved to the queen side. 

Leela's eval was close to 4 but from here on it gradually came down. Stockfish exchanged knight for bishop and Leela couldn't find a safe way to penetrate the pawn wall. On move 62 Stockfish gave a pawn and the a file opened, but the white pieces couldn't force their way through. The engines shuffled for a long time, on move 99 they exchanged a pair of rooks, on move 120 the remaining rooks were gone. Leela gave a bishop for pawns to break the pawn wall but evals were close to 0 and the game was adjudicated.

In game 20 the first few moves repeated game 19 with the locked center and open c file. Leela chose to exchange pawns on the king side and Stockfish's eval started to increase. There was a series of exchanges where Leela captured a pawn and both engines created advanced passers in the center. The black passer was unsupported and Stockfish captured it.

Stockfish gave a bishop and captured a rook for the passer. Leela tried to attack the white king but was not strong enough. The game reached a QRN vs QBN position, each engine had a passer.

Stockfish's progress was very slow, it let Leela capture the f passer as it thought how to break the bishop-pawn pair blocking the center. The bishop moved but was still a strong piece in the center. Stockfish managed to move the queen forward while keeping its king safe, on move 68 it finally exchanged knight for bishop. Stockfish pushed the h pawn and captured the black knight, the game ended a move before mate. Stockfish wins the game pair, it leads 5-2.

Season 27 superfinal games 1-10

After 10 games Stockfish leads 3-1 with 6 draws. Stockfish won the first two game pairs, continuing the trend of the premier division where it won 3/4 game pairs. Then Leela won a game pair, its first win of the season against Stockfish. Stockfish then won a third time and the gap after 10 games is 2 wins. In game 8, the reverse game in the pair Leela won, Stockfish was certain it was winning with eval over 3. Leela's eval stayed low as it steered the game towards a Q vs R ending and built a perfect fortress to hold a draw. It is very unusual to see Stockfish miss this as a draw, its eval remained high for a very long time. 

The opening book was created by Jeroen Noomen, details can be found here. Openings were taken from games of chess masters of the past, this season 23 of the openings were from Viktor Korchnoi's games.

Games 1-2 started with a 20-ply line in the Alekhine defense modern variation, played in high level human games. In game 1 the center was locked, there were no exchanges after the start except a pair of  minor pieces. On move 24 Leela opened the b file, it captured a pawn and created a passer but evals started to come down slowly. Stockfish blocked the passer with a knight, then placed the other knight on the h file and protected both knights with a bishop on the back rank. The engines exchanged all rooks and started to shuffle, on move 69 the engines exchanged a pair of knights, evals were close to 0. The game was adjudicated 20 moves later. 

In game 2 the engines repeated game 1 for 16 plys. The center was locked, Stockfish opened the b file and captured a pawn to create a passer, but in this game evals stayed high though stable. Leela placed its knights on the two board edges like in game 1, but couldn't protect both with a bishop because the c7 pawn blocked the diagonal. The engines shuffled, Stockfish's eval started to increase on move 34, Leela's eval reacted a few moves later. 

Leela exchanged pawns on the queen side, the white major pieces moved to the center. The engines started to exchange pieces and pawns on move 44 and the board opened up. After another series of exchanges the game reached a QRB vs QRB position. 

Stockfish pushed the passer forward and Leela lost a bishop to stop it. The game ended in a tablebase win. Stockfish wins the game pair, it leads 1-0. 

Games 3-4 started with a 22-ply line in the Nimzo-Indian, Rubinstein variation. In game 3 Stockfish opened the e file and gave a rook for a bishop. There were many early exchanges and the game reached a QR vs QB position on move 27. Stockfish blocked the center with a pawn and a bishop and the engines shuffled, Stockfish's eval dropped to 0. On move 46 Stockfish captured a pawn, then Leela gave a pawn and created a passer in the center. Stockfish blocked the passer with a bishop on the back rank, Leela wouldn't lower its eval enough for the draw rule. The engines reduced to a rook vs pawns endgame with black 4 pawns up and the game was adjudicated.

In game 4 the engines repeated game 3 for 21 plys, as in game 3 Stockfish was up a rook for a bishop. Evals jumped when Stockfish pushed pawns on the queen side and moved a rook to the 7th rank. Leela exchanged a pair of rooks and the game reached a QRB vs QBB position. 

Stockfish's eval increased slowly while Leela's eval jumped up and down. Stockfish did not take the b7 pawn, probably because it restricted the black LS bishop. Leela controlled the dark squares and had mate threats that Stockfish had to consider, very slowly the white king walked to the center. On move 60 Stockfish pushed the g pawn and opened the g file, then captured the b7 pawn and gave back the rook for a bishop. 

The white a pawn became a dangerous passer, Stockfish captured two more pawns and create more passers. Leela captured two pawns and traded bishops, it chased the white king but couldn't avoid a queening. The game ended in a tablebase win. Stockfish wins the game pair, it leads 2-0.

Games 5-6 started with a King's gambit, bishop's gambit variation, with black a pawn up and a bias for black. In game 5 the engines opened the e file, Leela opened the a file and the engines exchanged a pair of rooks. Evals came down as the engines played out a long PV agreement, Leela gave another pawn and created an advanced passer on the queen side. Stockfish captured the passer on the 7th rank, Leela captured a knight for a pawn. The game reached a QBN vs QB position and was adjudicated after queens were exchanged. In game 6 a series of exchanges opened the e file and exchanged most minor pieces. Leela blocked the e file with its bishop, the black pawns stayed back and the engines started to shuffle. Stockfish's eval dropped to 0, Leela's eval came down more slowly. The shuffle was extended with pawn moves, there were too many pieces for the draw rule and the game ended by repetition on move 98.

Games 7-8 started with a 22-ply line in the Torre attack, there was one minor piece exchange and white castled long. in game 7 Stockfish pushed pawns on the queen side and castled long. The engines played out a very long PV agreement, exchanging pawns and knights in the center. Leela had a passer in the center, Stockfish attacked it with many pieces and Leela had enough defenders. After a while the attention shifted to the black pawn on c5.

Stockfish chose to move its bishop to b5 and then protect the c pawn by pushing it to c4. Stockfish gave a pawn on the king side and captured the d passer, Leela shifted focus again and after a pawn trade it created a passer on the e file. Stockfish blocked the passer on the 6th rank, Leela captured the c pawn using a pin and then exchanged queens.

Leela kept its passer protected and exchanged a pair of rooks. Stockfish lost more pawns, the white king moved forward and Leela queened the passer. The game ended in mate.

In game 8 Stockfish thought for 47 minutes on its first move, and chose a different continuation. There were a few pawn exchanges in the center and Leela castled short. Stockfish's eval kept increasing while Leela's eval was low and stable. The black queen moved forward, Stockfish gave two pawns and a knight and opened the g file. Stockfish attacked the black king, Leela exchanged pieces and gave material and the game reached a QR vs RRB position. After exchanging rooks Stockfish pushed a passer and Leela gave the bishop for it. 

The resulting position was a black fortress, the black rook could not be moved and it protected the b5 pawn, the white pawns were blocked, the black king was perfectly safe and the white king could not approach the king side. Incredibly Stockfish missed this, its eval was over 3 and wouldn't come down. The engines shuffled until Stockfish's eval was low enough for the draw rule on move 128. Leela wins the game pair, Stockfish leads 2-1.

Games 9-10 started in a Queen's gambit declined sideline, played in human chess. In game 9 Stockfish exchanged minor pieces and queens early. Another minor piece exchange opened the c file and the engines exchanges all rooks through it. The game reached a N vs B ending with almost all pawns on the board, Stockfish's eval was 0 but Leela lowered its eval slowly. The game was adjudicated on move 97.

In game 10 Leela had problems developing its queen side, Stockfish gave a knight and opened the h file. Evals increased quickly as the black king was exposed, Stockfish was a piece down but Leela was playing with two pieces stuck on the queen side and unable to help, so effectively Stockfish had a material advantage attacking the black king. 

Leela moved its king to the center and it managed to move its bishop to free its queen side rook. However, the attack wasn't over. Stockfish moved its rook forward, after a few pawn trades the rook gave checks and Stockfish captured the black rook still on a8. The engines then reduced to a queen ending with white a pawn up.

Stockfish used the exposed black king to capture a pawn. Leela did the same with its queen but then Stockfish captured the a pawn and created an advanced passer. Leela lost its queen and the game ended in a tablebase win. Stockfish wins the game pair, it leads 3-1.

Season 27 premier division statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins

Final draw rate was 56.3%. 

Game termination

The three most common game termination causes were:
44.6% - TCEC draw rule
25.9% - Mate
21.4% - SyzygyTB

There were no crashes in the stage.

Moves per game

Median= 77
Average= 79.1

There were 33 games longer than 100 moves, the longest was 307 moves (Ethereal - Berserk, game 202, draw). 

Time per game (hours)

Median= 2:09
Average= 2:04

Openings

There were variable length book openings in this stage. The first letter of the ECO codes was distributed as follows: 

The engines had almost no freedom to choose the opening variant, all of the game pairs repeated the same ECO code and the opening variant twice.

Reverse pairs, wins

Reverse pairs, same moves

Pairs of reverse games diverged less quickly than usual, 19.6% diverged immediately out of book, 45.5% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 33 plys (Obsidian - Ethereal, games 80 and 108, Queen's Indian Petrosian system, Obsidian won as white) 

Season 27 premier division final results

Final Standings

Stockfish and Leela will play in the season 27 superfinal. Both engines led the league from the start, Stockfish was first and its lead over Leela and the rest of the engines only increased. Leela was still close to 3rd place in RR5, but since then it pulled away from the other engines. Stockfish won 22/28 game pairs without loss and with only 2 game losses, surprisingly it drew 4 game pairs against Obsidian. Leela lost 3 game pairs to Stockfish, and it won 15/24 of the game pairs without loss against the other engines.  

There were 3 engines in the race for 3rd place: Obsidian, Berserk and KomodoDragon. At the half way point Obsidian was in 3rd place with Berserk a point behind and KomodoDragon 2.5 points behind. Obsidian was without a game pair loss at this stage. After DRR3 Obsidian was still in 3rd place though it lost two game pairs, Berserk was still a point behind and KomodoDragon only 1.5 points behind. In the last DRR Berserk won 3 times with only one loss, while Obsidian lost 3 times and only won once. As a result Berserk finished in 3rd place. 

At the bottom of the table Seer was too weak for the division, it lost 23/28 game pairs and won only 2. Ethereal and Caissa were in the race for 6th place. At the half way point Caissa was ahead by 0.5 points, but in the second half Ethereal was better with 5 game pair losses and 4 wins, while Caissa had 7 game pair losses and one win. As a result Caissa joins Seer, to be relegated to league 1 next season.

Interesting games

game 174, Berserk - Ethereal: The engines castled in opposite directions, Ethereal pushed a pawn to a3 and captured a pawn on the king side. Berserk created a passer in the center after a knight exchange, the engines exchanged queens and Berserk captured the a3 pawn. On move 32 evals started to increase, Ethereal created a passer on the king side, Berserk captured pawns on the queen side and created a second passer. Berserk pushed the queen side pawn, Ethereal captured the passer n the center and the game reached a RRN vs RRN position. Both kings walked to block an opponent's passer, Berserk captured another pawn and exchanged a pair of rooks. Berserk captured the last black pawn, the game ended in a tablebase win.

game 177, KomodoDragon - Seer: The black king moved without castling, trapping the king side rook. The center was locked, the engines opened the a file and exchanged a pair of rooks. Seer moved its king to h7 to free the king side rook, KomodoDragon pushed pawns on the king side, gave a pawn and opened the f file. KomodoDragon regained the pawn and reduced to a rook ending, material was equal but the white rook was on the 7th rank and KomodoDragon had an advanced passer on g6. KomodoDragon captured pawns on the king side, Seer captured pawns on the queen side but it wasn't fast enough. The game ended in mate.

game 180, Leela - Berserk: Leela pushed the h pawn, developed the king side rook forward, Berserk castled long and Leela moved its king to the king side without castling. The center was locked and the engines mostly shuffled with one pawn exchange, evals slowly started to increase. Leela pushed pawns on the king side, on move 51 the was a pawn exchange there and then Leela captured a pawn. Leela had a passer on the king side, Berserk moved major pieces forward through the queen side but Leela surrounded its king with pieces to keep it safe. Leela gave the queen for a knight and queened the passer, after exchanging queens only rooks and knights remained, Berserk a pawn up but a knight down. Leela slowly pushed its last pawn forward, Berserk lost more material and the game ended in a tablebase win. 

game 182, Stockfish - Leela: See Featured game below.

game 184, KomodoDragon - Obsidian: KomodoDragon castled long and doubled queen and rook on the d file. When the d file opened the black king was in danger. Obsidian moved the queen forward and captured two pawns, KomodoDragon captured one pawn back and opened the c file as well. In a series of exchanges Obsidian traded rook for knight and then castled its king for safety. All major pieces moved to the queen side, KomodoDragon gave back a rook for a knight and the game reached a QRN vs QRN position. KomodoDragon had passers on the queen side, but it couldn't push them forward safely. It took almost 30 moves to reduce to a queen ending, then the white king and queen side pawns moved forward slowly. Obsidian couldn't avoid a queening followed by mate.

game 185, Obsidian - Seer: The center was locked, there were no exchanges after the start except for a pair of bishops. The engines locked the queen side, on move 37 Obsidian gave a bishop for a pawn and created a passer on the king side. Seer hid its king behind the white passer and gave back the piece. Obsidian captured another pawn and exchanged pieces until only QR vs QR were left. The white king moved forward and Seer could prevent the files opening. After exchanging rooks Obsidian drove the black queen away, chased the black king and mated.

game 187, Leela - Caissa: There were no exchanges after the start, the engines locked the center and queen side. The engines mostly shuffled until Leela exchanged a pair of pawns on the king side on move 40. Caissa tried to keep the king side closed but Leela exchanged pieces and opened the f file. Caissa gave a rook for a bishop to close the file again and created a passer in a QRN vs QNN position. Leela captured the passer, then created passers on the queen side. Caissa lost material and delayed with checks but it couldn't avoid a queening and mate.

game 191, KomodoDragon - Leela: The engines castled in opposite directions, the black king had weak pawn support and under direct threat after KomodoDragon opened the g file. Leela surrounded its king with pieces, after move 30 KomodoDragon's eval started to increase. Leela captured a pawn and its eval went down, but it was surprised on move 40 and its eval jumped. KomodoDragon placed a protected rook on e6, then reduced to a QR vs QR position. The white pieces were more active while Leela had to protect its exposed king, KomodoDragon captured pawns and reduced to a rook ending a pawn up. The game ended in a tablebase win.

game 193, Ethereal - Seer: The engines castled in opposite directions, Ethereal pushed pawns on the king side. The engines shuffled for a while and opened the e file, then Seer pushed pawns on the queen side and Ethereal locked pawns. Ethereal tried to attack the king side, Seer gave a rook for a knight and two pawns. Ethereal placed a rook on the back rank, then drove the black king forward. Seer lost a piece defending its king, then it lost more material and was mated.

game 194, Leela - Obsidian: The engines castled in opposite directions, Leela pushed pawns on the king side and exchanged a pair of pawns but Obsidian kept its king safe. Leela captured a pawn on the queen side, for a while the engines shuffled with evals increasing. Obsidian regained the pawn and after some more shuffling the game reached a QRB vs QRN position. After exchanging queens Leela gave a pawn and created connected passers on the queen side. Obsidian couldon't stop the passers, Leela queened and mated.

game 195, Berserk - KomodoDragon: The engines castled in opposite directions, Berserk pushed pawns on the king side. The engines exchanged most minor pieces, after a few pawn exchanges the f file opened and both engines had a passer. Berserk captured a pawn on the queen side and created another passer. Berserk pushed both passers to the 7th rank, both of them queened but in a series of exchanges KomodoDragon was only down a rook. Berserk exchanged pieces and the game ended in a tablebase win.

game 196, Stockfish - Caissa: Stockfish castled long and pushed pawns on the king side. The white queen moved forward, Caissa opened the h file and developed its king side rook through it, leaving its king in the center. Caissa captured a pawn and had a bishop pair advantage but the two white knights were much more active in the center. Stockfish trapped a black rook and captured it for a knight. In a series of exchanges the engines reduced to a RN vs BB position, Stockfish continued to exchange pieces and pawns until reaching a tablebase win. 

Standings after RR7: Stockfish +18, Leela +10, KomodoDragon Obsidian Berserk +1, Ethereal -4, Caissa -7, Seer -20. The two first places are determined, but 3rd place is a 3-way tie. Obsidian had a weak RR with 2 losses and only one win, allowing Berserk and KomodoDragon to get closer and tie the scores. Ethereal has a 3 win lead over Caissa in 7th place.

game 197, Seer - Caissa: The center was locked and both engines moved their king without castling. There were no exchanges after the start, after move 22 the engines exchanged a pair of pawns and a pair of bishops. The engines shuffled with evals slowly increasing, there was a minor piece exchange on move 46 and Caissa captured a pawn. On black rook was trapped blocked by its own king, after some more shuffling the queen side opened and Seer threatened the black king with its major pieces. Seer captured pawns and went a pawn up, then in a series of exchanges reduced to a knight vs pawns endgame. The game ended in a tablebase win.

game 198, Stockfish - KomodoDragon: KomodoDragon gave a knight for 3 pawns after the start, the engines castled in opposite directions. The engines opened the h file, then continued to exchange pieces until only RBN vs RB remained. KomodoDragon was 3 pawns up with two passers on the king side, Stockfish slowly captured pawns while keeping an eye on the black passers. By move 60 both engines had two pawns left, all passers. Stockifsh pushed its passers forward and after 15 more moves captured the remaining black pawns. Stockfish then queened and mated.

game 200, Leela - Ethereal: There were only a few exchanges after the start, one pawn exchange that opened the c file, and one minor piece exchange. The engines locked the center and evals were stable until move 28. Leela's eval jumped, it opened the g file and exchanged a pair of rooks. Ethereal blocked the file with a rook and was willing to give the rook for a bishop but Leela did not take it. The black king walked to the center, Ethereal's eval reacted much later, Leela exchanged rooks and captured a pawn. The white h pawn became a passer, the game reached a BB vs NN position and Leela created a second passer after an exchange. Ethereal captured one passer but lost a knight for the other, Leela created another passer, queened and mated.

game 201, Leela - Seer: Leela pushed a pawn to a3 and the engines locked the center. Leela had a space advantage and evals increased rapidly, it blocked the queen side and shifted focus to the king side. A minor piece exchange on move 29 opened the f file, after a while all rooks were exchanged. Seer had pieces trapped on the queen side, it gave a pawn to free a knight. After exchanging queens Leela had a passer on the king side and only BB vs BN were left. Leela exchanged bishop for knight, both engines created more passers but the white pawns on the king side were quicker and gave checks. Leela queened twice and mated.

game 202, Ethereal - Berserk: Ethereal had a space advantage in a closed position with castling in opposite directions. After a long shuffle the h file opened  but Ethereal let Berserk close the remaining files and protect its king. The engines continued to shuffle and the game was adjudicated on move 307.

game 205, Seer - KomodoDragon: The engines locked the center and the black king moved without castling to the king side. Seer gave a pawn and opened the b file, giving KomodoDragon doubled passers, then Seer castled its king. The engines shuffled for a long time, evals started to increase as Seer prepared a king side attack. On move 67 there was a pawn exchange on the king side, KomodoDragon pushed a passer on the queen side but it wasn't fast enough to be a threat. In a series of exchanges Seer captured pieces and the game reached a RBN vs R position, the engines continued to exchange pawns and pieces until the game ended in a tablebase win. There were two white wins in this pair.

game 207, Stockfish - Ethereal: The engines locked the center, Ethereal moved its king without castling and then the queen side was closed as well. Ethereal exchanged pawns on the king side, exposing its king, then moved its king to the center. Stockfish created advanced passers on the king side supported by a bishop, Ethereal gave a rook for the bishop and one of the passers. In a QRR vs QRB position Ethereal captured another passer but Stockfish captured 3 pawns in the center. Ethereal lost the bishop for another passer, the game ended in mate.

game 208, Berserk - Leela: Berserk pushed the h pawn and developed its king side rook forward. The center was locked and both kings did not castle, the white king moved to the king side and the black king stayed in the center. There were a few pawn and minor piece exchanges and evals started to increase. Leela captured a pawn with its queen on the queen side and Berserk opened the f file. The black queen was stuck far from the king, Berserk regained the pawn and the game reached a QRN vs QRN position. The exposed black king walked to the queen side, a series of exchanges reduced to a Q vs RN ending. Berserk captured pawns and pushed passers, the game ended in a tablebase win. There were two white wins in this pair. 

game 209, Berserk - Seer: Berserk castled long, there were no exchanges after the start and Seer kept its king in the center. After a minor piece exchange the black king walked to the queen side, after move 34 two pawn exchanges opened files on the queen side. The black king walked back to the center while Berserk moved major pieces to the a file and captured a knight. The game reached a RBN vs RN position, Berserk captured pawns and created a passer, then queened and mated.

Standings with 3 rounds to go: Stockfish +20, Leela +11, Berserk +3, Obsidian +1, KomodoDragon -1, Ethereal -6, Caissa -8, Seer -20. Berserk won twice, including against Leela, and it is now in 3rd place. Obsidian drew 4 times while KomodoDragon lost twice, including a loss to Seer. At the bottom of the division Ethereal and Caissa are a little bit closer, Caissa's loss to Seer prevented it from closing the gap even more.

game 216, Stockfish - Berserk: The center was locked, the engines opened the b file and exchanged a pair of rooks. Stockfish's eval started to increase, it pushed pawns on the king side and left its king without pawn support. Stockfish opened the h file and gave a bishop to further expose the black king, Berserk's eval jumped as well. Berserk surrounded its king with pieces and Stockfish captured a knight, the game reached a RB vs RN position. Stockfish captured pawns and was 3 pawns up, it queened twice and mated. 

Two rounds to go Berserk leads Obsidian by only 0.5 points. No change for Ethereal and Caissa.

game 217, Stockfish - Seer: The engines castled in opposite directions, Seer gave a pawn in the center and the engines opened the f file. Stockfish doubled rooks on the f file, after a while Seer exchanged a pair of rooks. This closed the f file but created a white passer. The game reached a QRB vs QRN position and Stockfish connected a second passer. Seer blocked the passers with pieces, Stockfish's progress was slow. It gave a pawn and made an opening on the queen side for the queen to move forward. Stockfish regained the pawn after 25 moves, the queen side opened and Stockfish captured another pawn after exchanging the minor pieces. Stockfish moved queen and rook to the 7th rank and mate followed.

game 218, Berserk - Caissa: The engines castled in opposite directions, Caissa pushed the e pawn and it became a passer. Berserk opened the g file and gave a rook for a bishop to expose the black king. Caissa moved pieces to defend its king, it gave back the material and the game reached a QRB vs QRN position. Berserk captured the black passer and exchanged queens, after trading pawns Berserk had an advanced passer on the queen side. Caissa lost the knight for the passer, the game ended in a tablebase win. 

game 219, Leela - KomodoDragon: The engines castled in opposite directions, Leela exchanged pawns and the d pawn became an advanced passer. KomodoDragon captured a pawn on the queen side, Leela opened the f file. Leela captured a rook for a knight, the game reached a QRR vs QRB position and KomodoDragon captured the white passer. Leela's progress was slow, the engines traded pawns and on move 54 queens were exchanged. Leela pushed a passer forward, KomodoDragon lost material and was mated. There were two white wins in this pair. 

game 220, Ethereal - Obsidian: The engines castled in opposite directions, Obsidian pushed the e pawn and it became a passer. Ethereal exchanged pawns on the king side ,the g file opened and the f pawn became a passer. Ethereal gave a rook for a bishop, its two bishops moved forward and threatened the black pieces. Obsidian gave a rook for a bishop, then gave the other rook for a knight and the game reached a QRB vs QBN position. Obsidian pushed the passer forward and Ethereal gave a bishop for it, then created two passers on the queen side. Ethereal used the exposed black king to capture a knight, Obsidian tried to delay and chased the white king. Eventually Ethereal found safety for its king, Obsidian lost material and the game ended in a tablebase win. 

After this round Berserk has a 1.5 points lead over Obsidian and is assured 3rd place. Ethereal has a 2 point lead over Caissa, Caissa will relegate with Seer.

game 223, KomodoDragon - Berserk: The engines castled in opposite directions, KomodoDragon gave a pawn and moved major pieces to the king side to threaten the black king. When a white knight joined the attack Berserk exchanged pieces, the game reached a RRB vs RRN position with equal material. Berserk had two passers and KomodoDragon had one with a pawn majority on the queen side. KomodoDragon captured one passer and exchanged a pair of rooks, the black king walked to the queen side. The white king walked to the king side and captured the other passer. KomodoDragon pushed its passer forward, there were more exchanges and the game ended in a tablebase win. There were two white wins in this pair. 

Featured game: Stockfish - Leela
game 182

Both engines castled long, Stockfish pushed the a pawn and gave it away. The engines locked the center and mostly shuffled, there was one knight exchange and evals slowly increased. On move 44 Leela gave a knight for a pawn and placed its major pieces on the b file to threaten the white king. 

Stockfish protected the b2 pawn and opened files on the king side to exchange a pair of rooks. The white queen moved forward on the king side and Leela had to protect its center pawns, then a series of exchanges on move 72 reduced to a bishop vs pawns ending with black two pawns up. 

Leela moved its king forward but Stockfish kept its pawns safe with its bishop. There was nothing to stop the white king from and slowly capturing black pawns, Stockfish queened a passer and mated.

Season 27 premier division, after RR6

Standings after RR6

Stockfish with another solid DRR with 5 game pair wins including a second win against Leela. Stockfish is still without a game pair loss in the division. Leela is in second place with 5 game pair wins and one loss. Obsidian came close to Leela after RR5, but it dropped back after RR6. It lost twice, to Leela and Caissa, these were its first losses of the division. KomodoDragon improved its score after two wins and one loss. Caissa is now in 7th place, Ethereal is in 6th place with a small gap between them, the relegation race is wide open.

Interesting games

game 114, KomodoDragon - Stockfish: The center was blocked, the engines exchanged all bishops. KomodoDragon kept its king in the center, it created a passer in the center after a pawn exchange. The engines opened the a file, KomodoDragon captured a pawn on the king side and Stockfish didn't take back to keep the files closed. However the f file opened and the white queen moved forward. Stockfish exchanged pieces and the game reached a RN vs RN position. Stockfish had a blocked passer on the 2nd rank, KomodoDragon pushed connected passers in the center. Stockfish couldn't stop the white passers, the game ended in mate.

game 115, Obsidian - Berserk: There were many early exchanges and the game reached a QB vs QN position. Evals were high and increasing despite the material equality and symmetric pawn structure. The black knight moved to the queen side to assist the queen, this left the black king alone and vulnerable. Obsidian managed to capture a pawn and then exposed the black king. It captured a second pawn and created a passer, then pushed it to the 7th rank. Obsidian avoided stalemate traps, Berserk lost more material and the game ended in a tablebase win.

game 117, Seer - Leela: Leela was a pawn up from the start, Seer grabbed a pawn to equalize but it was slow to develop its pieces. Evals jumped on move 21, Seer had a pawn majority on the queen side and it pushed pawns there. Leela captured a pawn after exchanging a pair of rooks. Leela blocked a black passer in the center, it had a strong bishop pair and Seer gave a rook for one of the bishops. The game reached a QB vs QR position, black a pawn up. Leela's passers were faster, Seer lost the queen and was mated.

game 121, KomodoDragon - Seer: The engines locked the center, there was one minor piece exchange and all pawns were on the board. Evals increased slowly, the king side was locked as well and the engines seemed to be shuffling. On move 41 there was another minor piece exchange, KomodoDragon moved a knight forward on the queen side and traded it for a rook. Then KomodoDragon had more pieces available and it captured the a pawn. The game reached a RB vs BN position, Seer moved its pieces to the queen side, the white rook managed to move safely to the 7th rank. After a minor piece exchange KomodoDragon had an advanced passer. Seer was paralyzed, it lost material and was mated.

game 124, Leela - Berserk: The center was locked and the engines opened files on the queen side. Evals were low until move 35, Berserk ignored Leela's double attack and was forced to give a knight for 3 pawns. The engines reduced to a RB vs R position, Leela protected its a pawn and moved the rook forward. Leela captured two pawns and the a pawn became an advanced passer. Berserk delayed but couldn't prevent a queening though Leela lost the rook, the game ended in mate.

game 126, Stockfish - Leela: Stockfish castled long, the engines exchanged most minor pieces on the center. The black king moved forward, the e file opened and all rooks were exchanged. The game reached a QB vs QN position and Leela tried to hold a fortress placing almost all its pawns on squares the white bishop couldn't attack. Stockfish used threats to the black king to slowly improve, after 24 moves it captured a pawn and a few moves later it created a pawn majority on the queen side. Leela's fortress collapsed and the queens were exchanged. Stockfish created a passer on the queen side, the black king stopped it but that left the king side open for the white king. The game ended in a tablebase win. 

game 129, Obsidian - Seer: The center was locked, all pawns were on the board and the engines exchanged a few minor pieces. The white queen moved forward on the king side and Obsidian kept its king in the center. Obsidian pushed pawns on the queen side until the queen side was locked as well and the engines shuffled for a while. The white queen moved back and the white king walked to the queen side. On move 40 Obsidian pushed the f pawn and opened the king side. The engines exchanged pieces, Obsidian gave a pawn and opened the c file as well. The game reached a RB vs RN position, Obsidian regained the pawn and created connected passers in the center. Seer captured the white passers but Obsidian created an unstoppable passer on the queen side. Obsidian queened and mated.

game 130, Ethereal - KomodoDragon: The center was locked, Ethereal gave a pawn on the king side and moved its king without castling. The engines mostly shuffled, a pawn exchange opened the b file, another opened the h file. On move 42 the engines exchanged the first pieces. A few moves later Ethereal regained the pawn and created a passer on the queen side. The engines shuffled for a long time, they exchanged a pair of rooks and queens, and on move 104 the game reached a RBN vs RBN position. After exchanging knights the white rook moved forward, KomodoDragon captured the passer but Ethereal captured the remaining 3 black pawns. KomodoDragon couldn't stop the white passers and the game ended in mate.

game 137, Ethereal - Seer: Ethereal was up a pawn with a queen side passer from the start. Seer attacked the passer and Ethereal gave it away but captured a rook for a knight. The engines exchanged queens and then mostly shuffled for a while. On move 57 Ethereal exchanged pawns on the king side and created a passer. The game reached a RR vs RB position, Seer gradually lost material and the game ended in mate.

game 138, Leela - Obsidian: see featured game below.

game 140, Stockfish - Caissa: The engines locked the center, after a pawn exchange on the queen side Stockfish moved its queen side rook to the king side. Caissa moved a rook forward on the queen side while Stockfish concentrated on the king side. Stockfish gave a knight for a pawn to weaken the black king defenses, all the white major pieces moved to the king side and the black king ran to the center. Stockfish traded RB for Q then moved a rook forward and exchanged rooks, it was two pawns up with 3 passers in the center. Caissa was busy defending its exposed king, the game reached a Q vs RBB position. Caissa lost a bishop for the two passers, then it lost the other bishop. The game ended in a tablebasde win.

Standings after RR5: Stockfish +12, Leela +7, Obsidian +4, KomodoDragon Berserk -1, Ethereal -2, Caissa -4, Seer -15. Stockfish won twice (including against Leela) and lost to KomodoDragon, Leela won 3 games (including against Obsidian) and lost once. As a result Stockfish's lead over Leela decreased a little but it is still significant. Obsidian came close to Leela but its loss to Leela increased the gap again. Berserk dropped after two losses (including against Obsidian). At the bottom Caissa is now 7th after Ethereal had a good RR with 2 wins. 

game 142, Stockfish - KomodoDragon: The center was locked and the engines exchanged all bishops. The engines exchanged pawns and both created a passer in the center. The engines shuffled for a while and closed the queen side, evals increased steadily. The game reached a QRN vs QRN position, on move 55 Stockfish found a way to move its queen through the black pawn line. Stockfish pushed the passer to the 7th rank and KomodoDragon lost a rook for it. KomodoDragon lost more material and the game ended in mate. There were two white wins in this pair. 

game 143, Berserk - Obsidian: There were no exchanges after the start and evals were stable. After move 19 the engines exchanged a pawns and a pair of rooks on the queen side, then a pair of pawns on the king side. Evals started to increase, Berserk captured a pawn and created a passer in the center. The game reached a RBN vs RBN position, Berserk captured a second pawn and created a passer on the queen side. Obsidian captured one passer and the knights were exchanged. The RB vs RB endgame was slow, after 20 moves Berserk captured a pawn, then gave a rook for a bishop. Obsidian couldn't stop a passer and the game ended in a tablebase win. There were two white wins in this pair. 

game 144, Leela - Ethereal: Ethereal captured a pawn and opened the e file early. A black rook moved forward to the h file, then Ethereal gave a bishop for a pawn to expose the white king. Leela protected its king and Ethereal captured a 3rd pawn. Leela exchanged pieces and the game reached a RB vs R position. Ethereal had 3 pawns on the king side and it pushed them slowly with the king supporting. The black rook was in front of the pawns and it got trapped, allowing Leela to capture a pawn and created a passer on the queen side. Leela stopped a black passer on the 2nd rank, the black rook blocked the queen side passer and Leela captured the remaining black pawns. The game ended in a tablebase win. 

game 148, KomodoDragon - Caissa: There was a pawn exchange and a few minor piece exchanges after the start. KomodoDragon captured a pawn in a series of exchanges on the queen side, Caissa pushed a pawn to h3 and the game reached a QBN vs QBN position. More exchanges reduced to a rook ending, the white king moved forward in the center. Caissa traded pawns and the h pawn became a passer. KomodoDragon had a passer on the queen side, after a while both passers were captured and this left two white pawns against one black in the center. The 7-man position was played for another 30 moves before reaching a 6-man tablebase win.

game 150, Caissa - Obsidian: The engines castled in opposite directions, Caissa pushed pawns on the king side and Obsidian locked pawns to keep its king safe. There many exchanges and the game reached a RRB vs RRN position, Obsidian created a passer on the king side and Caissa created a passer in the center. Caissa gave a pawn and connected a second passer, Obsidian captured a second pawn to created 3 connected passers on the king side. The white passers were more dangerous, Obsidian gave a rook to capture them. Caissa captured 2 advanced black passers, then used its piece advantage to attack the black pieces and pawns. Obsidian lost more material and the game ended in a tablebase win.

game 151, Stockfish - Ethereal: There were no exchanges after the start, the engines locked the center, Stockfish castled long and Ethereal kept its king in the center. Ethereal pushed a pawn to a3, on move 26 the engines exchanged minor pieces, then there were several pawn exchanges and Stockfish created a passer in the center. On move 33 evals jumped, Stockfish pushed the passer with the queen supporting and Ethereal gave a rook for a knight to stop the passer. In a QRB vs QBN position Stockfish attacked the black king and exchanged queens. It was a slow endgame, after 40 moves Stockfish was a pawn up with a passer. It gave the rook for a knight to queen the passer, the game ended in mate.

game 153, Berserk - Seer: Berserk castled long and the black king moved without castling. Seer pushed a pawn on the queen side, Berserk gave a pawn and hid its king behind the black pawn on b2. Berserk pushed pawns on the king side and opened the f file, it gave two more pawns and captured a rook for a knight. After opening the d file the black king came under attack, the game reached a RRB vs RBN position and Berserk captured pawns until it was two pawns up. Seer lost more material and was mated.

game 155, Ethereal - Caissa: Ethereal pushed pawns on the king side yet castled short, Caissa kept its king uncastled. The engines exchanged all knights, Ethereal pushed a pawn to f6 and trapped the black king side bishop. Caissa couldn't develop its king side rook and it traded the rook for a bishop. The d file opened and the black king was in danger, Caissa gave its second rook for a bishop as well and closed the d file. In a QRR vs QBB position both kings walked to the queen side, Ethereal exchanged queens and captured a bishop. The game ended in mate.

game 158, KomodoDragon - Ethereal: The engines castled in opposite directions and the center was locked. One pair of pawns and one pair of bishops were exchanged after the start. After exchanging another pair of pawns the engines shuffled for a long time with stable evals. A minor piece exchange extended the shuffle, on move 95 KomodoDragon captured a pawn and evals slowly started to increase. On move 109 KomodoDragon gave a rook for a knight and captured another pawn, then it captured a third pawn and created passers on the queen side. KomodoDragon captured a rook for a knight and the game reached a B vs N position. Ethereal couldn't stop the white passers, it lost material and was mated. There were two white wins in this pair. 

game 160, Stockfish - Berserk: The center was locked and there was one pawn exchange on the king side. After a while Berserk castled short and Stockfish decided to castle long. The engines shuffled with stable evals, after move 40 evals started to increase. Stockfish pushed a pawn to h7, Berserk hid its king behind the pawn to keep the h file closed. Stockfish gave a pawn and opened the queen side, then captured 3 pawns and reduced to a RRN vs RRN position with 3 passers. The engines exchanged a pair of rooks and Berserk captured the h passer. Stockfish gave another passer and pushed a third to the 7th rank. The white king moved forward and Berserk lost a rook, the game ended in mate.

game 161, Stockfish - Seer: The black queen moved forward, Seer captured a pawn and Stockfish captured a rook for a knight. Evals slowly increased, the engines slowly exchanged pawns and pieces and opened files. Seer created a passer in the center and captured another pawn. Then Seer gave a knight for a third pawn and connected a second passer. Seer tried to push the passers forward, Stockfish captured one and then exchanged queens to reach a RBN vs RB position. Stockfish captured the remaining black passer, then used the extra piece to slowly capture more pawns. The game ended in a tablebase win. 

game 163, Leela - KomodoDragon: The engines locked the center, there was one pawn exchange on the king side and a few minor piece exchanges. Evals increased slowly, on move 41 Leela locked the queen side and then KomodoDragon captured a pawn, its a pawn became a passer. The white king walked to the queen side, after a minor piece exchange Leela shifted all its major pieces to the king side. The g file opened and KomodoDragon moved its major pieces to protect its king. Leela captured the black a pawn, the white king moved forward and after a pawn trade the white c pawn became an advanced passer. Leela moved pieces to the opening on the queen side, KomodoDragon captured a pawn but lost a bishop or the white passer. The game reached a QRB vs QR position, KomodoDragon lost more material and the game ended in a tablebase win.

Featured game: Leela - Obsidian
game 138

Leela was up a pawn with a queen side passer from the start, its king moved without castling and found safety on g2. There were many piece exchanges early and the game reached a QRN vs QRN position. 

Evals started to increase after move 25, Leela secured its passer and slowly turned its attention to the king side, pushing its pawns there. On move 52 Leela opened the f file and gave a pawn to open the center. The engines exchanged queens and closed the f file but Leela captured a pawn and created passers on the king side. 

Obsidian captured pawns in the center and had 4 connected passers, but they were too slow and not supported enough. Leela pushed the a pawn to the 7th rank and Obsidian lost its rook for it. The black passers were not fast enough Leela trapped the black king and the game ended in mate.

Season 27 premier division, after RR4

Standings after RR4

Stockfish extended its lead at the top with 5/7 game pair wins and no loss. Leela dropped back after only two game pair wins, also without loss (it lost as black against Obsidian and Caissa). Obsidian is alone on 3rd place after two game pair wins without loss, Obsidian has no game pair losses in the division until now. Berserk with two game pair wins and two losses dropped to 4th place. At the bottom of the table KomodoDragon and Caissa have a small lead over Ethereal in 7th place, in the fight against relegation. 

Interesting games

game 59, Obsidian - Berserk: There were many early exchanges and the game reached a RBB vs RBN position. Evals increased very slowly, Obsidian had a bishop pair advantage but with many pawns on the board the bishops were less effective. It took 35 moves to exchange two pairs of pawns, Berserk had a passer but the white bishops had more space. Obsidian created a passer with another pawn trade, then exchanged rooks. Obsidian captured a pawn and created another passer, Berserk couldn't stop both and started to lose material. The game ended in a tablebase win.

game 65, KomodoDragon - Seer: The center was locked, Seer caputred a pawn and the engines shuffled for a while. Evals slowly increased. KomodoDragon regained the pawn, there was a minor piece exchange and the engines shuffled again. On move 64 KomodoDragon started to open the king side, it captured a rook for a bishop and the game reached a QRR vs QRB position. The black king was under threat, Seer lost more material and was mated.

game 72, KomodoDragon - Obsidian: The center was locked and the engines opened files on the queen side. Obsidian tried to be active on the a file but nothing came out of it, eventually KomodoDragon exchanged a pair of rooks and the focus shifted to the king side. The white king walked to the queen side and evals slowly increased, KomodoDragon captured a pawn and opened the g file. The game reached a QBN vs QBN position, both engines created a passer and queens were exchanged. Obsidian lost material to stop the two white passers while KomodoDragon was on time to block the black passer. The game ended in a tablebase win.

game 73, Obsidian - Seer: Obsidian pushed pawns on the king side, both engines castled long. After a few pawns exchanges on the king side Obsidian started to attack the queen side. After a series of exchanges the game reached a Q vs RR position. Obsidian captured a pawn and created connected passers, and Seer couldn't stop their slow march supported by the king. Obsidian queened and mated.

game 75, Leela - Caissa: Leela castled long and pushed pawns on the king side. The black king was stuck in the center, Caissa pushed pawns on the queen side and evals increased. Leela captured a pawn, Caissa tried to find safety for its king on the queen side surrounded by pieces. Caissa regained the pawn and gave a rook for a knight, the game reached a QRR vs QRB position. Leela traded two rooks for the black queen, then captured two pawns. Caissa lost more material and the game ended in a tablebase win.

game 78, Caissa - Berserk: The engines locked the center, there were no exchanges after the start. There was a pawn exchange on move 36, after move 45 the engines started to exchange pieces and pawns. Caissa was two pawns up, it gave one pawn to create a passer and pushed it to the 7th rank. Berserk captured the passer and gave a rook for a knight, the game reached a RB vs BN position. Each engine had one pawn left, the 8-man endgame was slow but eventually Caissa reduced to a tablebase win.

game 80, Obsidian - Ethereal: Obsidian pushed pawns on the king side and castled long. Ethereal was a pawn up but its king remained uncastled. After exchanging a pair of rooks the engines locked the center. Obsidian regained the pawn, after exchanging queens the engines began to shuffle in a RBB vs RBN position. Obsidian captured a pawn, there were a few pawn exchanges and then the rooks were exchanged, evals started to increase. Obsidian had a blocked passer on the king side, it pushed the a pawn forward, then used the bishops to drive the black king away. Obsidian capture another pawn and the a pawn became an advanced passer. Ethereal lost material and was mated.

game 81, Ethereal - Seer: The center was blocked, the black king moved without castling and Ethereal castled long. Seer tried to develop the king side rook through the h file but it was still confined to the corner area. After a while Seer gave a knight for pawns, a series of exchanges opened the board and queens were exchanged. Ethereal was down to 2 pawns but one was a passer on the queen side. It took Ethereal some time to capture a pawn and then reduce to a RBN vs RB position. With the extra piece Ethereal captured all the black pawns, the game ended in mate.

game 82, Leela - Obsidian: The center was locked and the white queen moved forward on the king side. Obsidian moved its king to the king side without castling, Leela placed the queen on f6 and pushed pawns on the king side. Obsidian drove the queen back, Leela castled late and gave a pawn on the queen side. Obsidian felt danger in the center, the black king walked to the queen side. Leela then cleared all the pawns on the queen side and queens were exchanged. Obsidian had to protect its king, Leela gave a rook for a knight and captured all black pawns. In a RBN vs RRN position Leela had 3 passers, after queening twice the game ended in a tablebase win.

game 83, Berserk - KomodoDragon: The black king remained in the center and the black king side pieces were slow to develop. The queen side was open and KomodoDragon castled short eventually. Berserk threatened mate and KomodoDragon exchanged pieces until only RRB vs RRB remained. The engines traded pawns and Berserk was a pawn up with a passer on the queen side. After exchanging a pair of rooks the white king moved to support the passer. Berserk managed to capture a second pawn and reduce to a rook ending, it queened and mated.

game 84, Stockfish - Caissa: The center was locked and the white queen moved forward on the king side. After the white queen retreated Caissa castled long, the white king stayed in the center and Stockfish pushed pawns on the queen side. The a file opened and Stockfish doubled queen and rook there, then castled short. Caissa gave a rook for a knight and tried to attack the white king, Stockfish gave back the material and kept its king safe. Caissa captured a pawn and moved a passer to the 2nd rank, Stockfish captured the passer and exchanged queens. The game reached a RB vs RB position with white a pawn up, Stockfish captured a second pawn and exchanged rooks. The bishops were of opposite color but Stockfish had an advanced passer that Caissa couldn't stop, the game ended in a tablebase win.

Standings after RR3: Stockfish +7, Leela +5, Obsidian +2, Berserk 0, KomodoDragon -1, Ethereal -2,  Caissa -3, Seer -8. Stockfish still leads but it had just one win in RR3, drawing as white against Obsidian and Leela. Leela only reduced the gap by one win, it had 2 wins and drew as white against Berserk. Obsidian is alone in 3rd place, it won 3 games and lost 2. Berserk dropped to 4th after one win and two losses.

game 86, Stockfish - KomodoDragon: There were only a few pawn exchanges after the start, the engines opened files on the queen side and Stockfish created a passer. KomodoDragon gave a rook for a bishop and captured the passer. The game reached a RRN vs RBB position, after a while the engines exchanged a pair of rooks and cleared the queen side pawns. Evals increased as Stockfish moved its king to the center of the board, it managed to trade knight for bishop. The white king moved forward and the game ended in mate.

game 87, Berserk - Obsidian: The engines opened the d file, Berserk had a protected pawn on e5. In a series of exchanges Obsidian captured the e5 pawn and placed a rook on the d file, while Berserk had a bishop pair advantage. The game reached a RBB vs RNN position, Berserk had a pawn majority on the queen side, it pushed the pawns forward and the black knights moved to block and defend. Berserk exchanged a bishop for a knight, gave a pawn and moved the rook to the 7th rank. Then Berserk captured all black pawns on the king side and created a passer there. After reducing to a rook ending Obsidian couldn't avoid a queening and mate. There were two white wins in this pair.

game 88, Leela - Ethereal: There were no exchanges after the start and the center was locked. A few pawn and minor piece exchanges opened the center and the engines exchanged a pair of rooks. After a while a series of exchanges reduced to a QB vs QB position with white a pawn up. Ethereal had doubled passers on the queen side, Leela captured another pawn and created passers in the center and king side. After exchanging queens Leela captured another pawn, the bishops were of opposite color but Ethereal couldn't stop all the passers. The game ended in mate.

game 89, Leela - Seer: A pawn exchange opened the b file, all pieces were on the board until move 28. Evals were stable for a long time and the engines mostly shuffled. The engines locked the king side and evals started to increase after move 50. All rooks were gone, Leela slowly cleared the queen side and moved its queen and knights there. Seer tried to block, Leela captured a knight for a pawn and the game reached a QBN vs QB position. Seer had passers but they were too slow, it couldn't prevent a queening and mate.

game 92, KomodoDragon - Caissa: KomodoDragon pushed a pawn to h6 and Caissa castled short anyway. KomodoDragon kept its king in the center, a pawn exchange opened the g file and Caissa moved pieces to protect the black king. KomodoDragon captured two pawns on the queen side and created passers, the engines exchanged pieces until reaching a queen ending. Caissa managed to get a pawn back but the engines continued to trade pawns, the game ended in a tablebase win.

game 95, Stockfish - Ethereal: The engines exchanged most minor pieces and castled in opposite directions. All pawns were on the board, the center and queen side were closed and the appeared to be heading for a draw. On move 27 Ethereal made a mistake that allowed Stockfish to open the king side. After a series of exchanges only QR vs QR were left, Ethereal had an advanced passer that was blocked by the white king, Stockfish had two passers. Ethereal's eval started to increase much too late. The black rook blocked a passer, Stockfish opened the queen side and captured 4 pawns. There were no black pawns left, Stockfish attacked the black king, Ethereal lost more material and the game ended in a tablebase win.

game 97, Berserk - Seer: The center was locked, queens were off early and Berserk kept its king in the center. Seer pushed pawns on the queen side, letting a white knight to move to b5. The white king walked to a4 and Berserk doubled rooks on the h file. When it was ready Berserk gave the knight for a pawn, opened the h file and captured two more pawns on the king side. Berserk had two advanced passers and the white king moved to c6 to support one. Seer captured the passers and the white king captured two black pawns on the queen side. The game reached a RB vs RNN position with white 4 pawns up. Berserk slowly pushed a passer, Seer captured the passer but lost material and was mated.

game 100, Obsidian - KomodoDragon: The center was locked, Obsidian pushed pawns on the king side and kept its king uncastled. Pawn exchanges exposed the black king and Obsidian moved a pawn to g6. The pressure increased on the king side, KomodoDragon exchanged pieces and the game reached a RRB vs RBN position with black a pawn up. Evals increased slowly, both engines moved a rook forward and KomodoDragon created a passer. KomodoDragon tried to defend all its pieces and pawns, while slowly pushing the passer forward. Obsidian captured the passer on the 3rd rank, then the black fortress collapsed and Obsidian mated. There were two white wins in this pair.

game 103, Caissa - Leela: Caissa castled long and Leela kept its king uncastled. There were no exchanges after the start, Caissa slowly pushed pawns on the king side. On move 24 the exchanges started on the king side, Caissa captured a pawn and opened the h file. After another series of exchanges the game reached a QRN vs QRN position. Leela had a passer in the center but its king was exposed on the 7th rank. Leela tried to keep the white pieces away, eventually Caissa gave 3 pawns and broke the center. The white pieces moved forward, Leela lost material and only QN vs Q remained. Caissa captured pawns and the game ended in a tablebase win. There were two white wins in this pair.

game 104, Stockfish - Berserk: See featured game below.

game 105, Stockfish - Seer: Stockfish kept its king uncastled, it created a passer in the center after a knight exchange. The queen side was blocked, the white king walked there while Stockfish moved its pieces to the king side. Stockfish pushed pawns on the king side and eventually captured a pawn and created another passer. The game reached a QRB vs QRB position and the engines traded pawns. Seer captured the white passers, but its king was too exposed and the white king was completely safe. Stockfish attacked with queen and rook and managed to capture the black queen for the rook. The game ended in mate.

game 110, Obsidian - Leela: The center was locked and the white queen moved forward on the king side. Leela moved its king without castling, the drove away the white queen. There were a few minor piece exchanges, all pawns were on the board and evals increased very slowly. The first pawn exchange was on move 35, Obsidian opened the center and captured a pawn on the king side. The game reached a QRN vs QRN position, Obsidian was a pawn up with a passer on the king side. Obsidian captured a second pawn and created a passer on the queen side. Leela lost more material and the game ended in a tablebase win. There were two white wins in this pair. 

Featured game: Stockfish - Berserk
game 104

Stockfish castled long and Berserk kept its king uncastled. Berserk pushed the h pawn as well as pawns on the queen side, the black queen moved forward on the queen side. The engines exchanged most minor pieces but there were no pawn exchanges after the start. 

From move 27 evals started to increase, Stockfish drove the black king back, then captured a pawn and opened the d file. The game reached a QR vs QR position, the black king was exposed to attack through the open d file and Stockfish used this to exchange queens. The black king walked to the king side to protect the pawns there.

Stockfish captured a second pawn and created connected passers on the queen side. The black king was too far to help, Berserk regained one pawn and pushed a passer to the 2nd rank but it wasn't enough. Eventually Stockfish lost the rook but queened twice and mated.