Season 26 premier division, after RR4

Standings after RR4

Stockfish and Leela are tied in the lead, both after only 3 game pair wins in the second DRR. Leela closed the gap after beating RubiChess in both games, Stockfish only drew against Stoofvlees after an unexpected loss when playing black. Berserk increased the gap from KomodoDragon after beating it in a game pair for the second time. At the bottom Seer beat Ethereal and is now in 5th place, RubiChess beat Seer but lost more games and dropped to 7th.

Interesting games

game 64, Leela - RubiChess: The black king moved without castling, RubiChess captured a pawn and created a passer on the queen side. Despite this Leela castled long and used the black pawns as shields for its king. RubiChess gave back the pawn and Leela slowly pushed pawns on the king side, driving away the black pieces until it created a passer on g6. After some preparation Leela captured a pawn and attacked from the queen side. RubiChess gave a rook for a bishop and the game reached a QR vs QB position. RubiChess captured the white pawns on the king side but Leela created two passers. After exchanging queens Leela queened a passer and mated.

game 70, Berserk - Ethereal: The engines castled in opposite directions and gradually exchanged pieces and pawns. Berserk traded a rook for a bishop and two pawns, the game reached a QBN vs QRB position and white had 3 connected passers on the queen side. Evals were stable until Ethereal gave a bishop for two pawns on move 51. Berserk still had one passer, after reducing to a BN vs R ending it pushed the passer forward while protecting its other remaining pawn as well. Ethereal couldn't prevent a queening and the game ended in a tablebase win.

game 72, RubiChess - Seer: There were no exchanges after the start, the center was blocked and the engines played behind their pawn lines. RubiChess' eval increased very slowly, on move 40 the first minor pieces wee exchanged. Seer gave a pawn and RubiChess created a passer on the king side, then the pieces shifted to the queen side. More pieces were exchanged and evals increased faster, Seer captured the passer and the game reached a RB vs RB position. The engines traded pawns and RubiChess created more passers. Seer couldn't prevent a queening and mate.

game 74, KomodoDragon - RubiChess: There were no exchanges after the start, the engines formed long pawn lines that blocked the center and king side. After some shuffling the engines exchanged a pair of bishops and opened the a file. KomodoDragon placed all its major pieces on the open file, then in a series of exchanges the engines traded Q for RBN. The white pieces threatened the black king and queen , RubiChess gave its queen for a rook and reduced to a BNN vs N position. RubiChess lost the knight for a passer, KomodoDragon queened another passer and mated.

game 77, Stockfish - Berserk: See featured game below. 

Standings after RR3: Stockfish +8, Leela +7, Berserk +1, KomodoDragon 0, Seer -2, Ethereal RubiChess -3, Stoofvlees -8. This RR had more draws with only 8/28 decisive games. Both Stockfish and Leela drew a game in white against the other engines, though there was a black bias in Stockfish's game against Ethereal.

game 86, Berserk - RubiChess: The engines exchanged most minor pieces and blocked the center. RubiChess opened the king side and Berserk had a passer there. The game reached a RRB vs RRB position and evals started to increase. Berserk captured a pawn, RubiChess created a passer in the center. Berserk gave the passer and created another on the queen side, then exchanged a pair of rooks. The black king was in danger, RubiChess lost its bishop. The black passer was not strong enough and the game ended in mate.

game 92, RubiChess - Leela: Leela castled long even though the white queen had free access to d6. Then it curiously decided that its king should walk all the way back to the king side. Evals came down and the engines shuffled for a long time. On move 62 RubiChess captured a pawn and opened the center. Then in a series of exchanges the engines reduced to a Q vs RRN position with white 3 pawns up. RubiChess quickly captured 2 more pawns, it was 5 pawns up though two pairs were doubled. On move 77 RubiChess pushed a pawn and Leela's (negative) eval started to jump. The white pawns advanced but Leela began to capture them, it was only down two pawns with one black pawn left. Leela pushed its pawn forward and captured two more white pawns, then RubiChess lost its queen and the game ended in a tablebase win. Leela won this game pair from both sides.

game 93, Stockfish - RubiChess: The engines castled in opposite directions and the center was blocked. Stockfish opened the queen side and captured a pawn despite the fact that its king was exposed. Stockfish created a passer on the queen side, then in a series of exchanges RubiChess managed to capture the passer and trade a rook for two minors. RubiChess had a bishop pair but one of the bishops was in trapped in the corner by another white passer. The engines traded pawns and eventually RubiChess gave its trapped bishop for a passer. This created a new passer for white, Stockfish pushed it to the 7th rank and saw the win. RubiChess delayed with checks but eventually lost material and the game ended in a tablebase win.

game 94, Leela - Seer: There were only a few exchanges after the start, Leela pushed pawns forward and had more space. On move 42 Leela gave a pawn and through a series of exchanges created connected passers in the center. Seer had a blocked passer on the king side, after a while Seer gave a pawn and created a passer on the queen side. Leela captured one passer, Seer pushed the other to the 2nd rank and then gave a knight for the two white passers in the center. Leela captured the black passer, after exchanging queens Seer lost more material and was mated.

game 95, Berserk - KomodoDragon: Berserk was a pawn up from the start, there were many exchanges after the start including queens and KomodoDragon regained the pawn. The queen side pawns were mostly cleared, each engine had a passer there. The game reached a RBN vs RNN position, after some shuffling Berserk captured the black passer and KomodoDragon traded bishop for knight. After a long shuffle evals started to increase on move 105. The engines blitzed, Berserk managed to capture a pawn and created connected passers on the king side. KomodoDragon captured the queen side passer, but after the white king came to support the king side pawns were unstoppable. Berserk queened and mated.

game 97, Stoofvlees - Stockfish: Stoofvlees castled long and Stockfish moved its king to the king side without castling. The engines opened the queen side and exchanged queens, Stockfish gave a pawn and created a doubled white passer on the king side. Stockfish hid its king behind a passer and Stoofvlees trapped the king on the h file. The game reached a RBN vs RBN position, Stoofvlees captured pawns and exchanged knights. It was 4 pawns up with no black pawn left, after queening the game ended in a tablebase win. There were two white wins in this game pair.

game 101, Stockfish - Seer: There were only a few exchanges after the start, a pawn exchange opened the b file, then a knight exchange closed it back. Stockfish pushed pawns on the king side, after some shuffling evals started to increase. Stockfish moved a rook forward, the engines traded pawns and Seer created two passers on the queen side. Stockfish had a passer in the center, it captured a pawn and created a passer on the king side. The game reached a RB vs RB position, Stockfish captured more pawns and had a tripled pawn wall on the f file. The black king was trapped and the game ended in mate.

game 110, Seer - Ethereal: Ethereal had an isolated passer in the center, Seer pushed pawns on the king side and moved its king forward. After some shuffling the engines exchanged pieces and reduced to a rook ending with white a pawn up. Ethereal had a passer on the queen side and it moved its king there as support. Ethereal captured two pawns and pushed its passer to the 2nd rank but there it was stopped. Seer created a second passer on the queen side and Ethereal couldn't stop their advance, the game ended in a tablebase win.

Featured game: Stockfish - Berserk
game 77

The white queen moved forward on the king side and the black king moved without castling, trapping the king side rook. Stockfish moved both its rooks to the f file, after move 21 it gave two pawns on the king side while evals increased. 

Berserk managed to free its king side rook, the king side opened with a series of exchanges where Berserk gave a rook for a knight. Stockfish was still two pawns down but with the g file open it limited the black king to the h file.

Both kings were exposed but the black king was under threat. After some preparation Stockfish exchanged a pair of rooks and saw the win in a QRB vs QNN position. Stockfish cleared the king side pawns, Berserk lost material and was mated.

Season 26 premier division, after RR2

Standings after RR2

Stockfish and Leela are leading, Stockfish won all its game pairs against the other 6 engines while Leela won 5/6 game pairs with one draw against Ethereal. They drew their head to head games. So far Stockfish and Leela are in a league of their own, KomodoDragon appears to be out of the top3 that we have seen for several seasons. Berserk is in third place with 3 game pair wins within the bottom 6 engines, KomodoDragon is only 4th with two wins and one loss. Stoofvlees is the only engine without a game pair win, it seems to be the weaker engine of this division.

Interesting games

game 3, Seer - Stoofvlees: In a series of exchanges the engines reduced to a QB vs QB position and Seer went two pawns up. Seer had one passer, after 20 moves of checks and shuffling it pushed the passer. After another 15 moves Seer created a second passer, Stoofvlees gave material and the game ended in a tablebase win.

game 5, Stockfish - Ethereal: There were almost no exchanges after the start, Stockfish pushed pawns on the king side and Ethereal pushed pawns on the queen side. In a series of exchanges on move 23 Stockfish gave a rook and pawn for a bishop, then captured a knight for two pawns. After another series of exchanges the game reached a RBN vs RB position with black two pawns up. Stockfish captured a pawn and attacked the black king, Ethereal exchanged rooks. Stockfish captured two pore pawns and created a passer, the game ended in a tablebase win.

game 8, Leela - RubiChess: Leela managed to trap both black bishops on the back rank in the king side. RubiChess captured pawns and its queen moved forward to attack. Leela surrounded its exposed king with pieces, then in a series of exchanges the engines traded queens and a knight for a rook. Leela captured a trapped bishop, the game reached a RBB vds RB position with black 3 pawns up. Leela captured pawns and promoted a passer to a rook, which RubiChess refused to give a rook for. Leela queened another passer and the game ended in mate.

game 12, Ethereal - Stoofvlees: The engines opened the queen side and Stoofvlees was up a pawn. The black king walked to the king side and the king side rook was trapped. Ethereal doubled rooks on the e file and moved a rook to the 7th rank. The ga,me reached a QRB vs QRB position, Ethereal captured pawns until it was 3 pawns up. The engines reduced to a B vs R ending and the game ended in a tablebase win.

game 13, Stockfish - Stoofvlees: Stoofvlees captured a pawn but it had a disconnected forward bishop. When the black queen moved to protect the bishop Stockfish attacked, it doubled rooks on the d file and moved one rook forward. Stockfish gave a rook for a knight and attacked the exposed black king. Without a material advantage Stockfish used its strength on the light squares to mate.

game 14, Berserk - Ethereal: There were a few exchanges after the start, the engines exchanges minor pieces and opened the a file. The center was blocked and the engines exchanged a pair of rooks. After some shuffling the engines reduced to a QN vs QB position, Berserk captured a pawn and created a passer. Ethereal exchanged minors and delayed with checks but couldn't avoid a queening and mate.

game 15, Leela - KomodoDragon: Leela captured a pawn and created a passer in the center. In a series of exchanges KomodoDragon regained the pawn and opened the queen side. The game reached a RBN vs RBN position, KomodoDragon had a pawn majority on the queen side but Leela blocked the pawns. After exchanging knights KomodoDragon created connected passers, Leela captured a pawn and reduced to a rook ending. Leela gave the rook and queened a passer, the game ended in mate.

game 16, RubiChess - Seer: There were a few exchanges after the start, RubiChess created a central passer after the first pawn exchange. The engines gradually exchanged pieces and pawns, The game reached a RBB vs RBB position. RubiChess pushed pawns on the king side, Seer tried to counter by creating a pawn majority on the queen side. RubiChess exchanged a pair of bishops and captured a pawn, it pushed pawns forward and Seer lost its bishop. The game ended in mate.

game 18, KomodoDragon - RubiChess: The black queen was out early and RubiChess castled long. After exchanging queens RubiChess gave a rook for a bishop and pawn. KomodoDragon moved a rook to the 7th rank and the game reached a RRN vs RNN position. Both white rooks were active, KomodoDragon managed to capture a pawn and create a passer. After exchanging a pair of knights KomodoDragon pushed its passer, it gave a rook for a knight but RubiChess lost its rook for the passer. The game ended in a tablebase win.

game 21, Stockfish - Berserk: There were no exchanges after the start, the engines formed long pawn lines across the board. There was one knight exchange on move 31 and then the engines opened the a file. Stockfish moved all its major pieces to the a file and after some preparation exchanged a pair of rooks. Stockfish was patient, eventually it gave a knight to create a passer. Berserk lost a rook for the passer and the engines reduced to a RB vs BN position. Stockfish created another passer that cost Berserk its knight. The game ended in a tablebase win.

game 22, Leela - Stoofvlees: Leela castled long and both queens moved forward. The white queen captured a pawn on the queen side and Stoofvlees castled short. The engines opened files in the center, then in a series of exchanges reduced to a QN vs QB position. Both kings were exposed, Lela had a passer in the center. Stoofvlees delayed with checks but Leela managed to push its passer and Stoofvlees lost its bishop. Stoofvlees lost more material and the game ended in a tablebase win.

game 23, RubiChess - Ethereal: The engines castled in opposite directions and the center was blocked. After all bishops were exchanged RubiChess opened the f file and Ethereal opened the b file. RubiChess captured a rook for a knight and moved a rook forward on the queen side. RubiChess captured a pawn and created a passer, the game reached a QRN vs QNN position. Ethereal created a passer on the king side, its queen attacked the exposed white king and gave checks. However, eventually RubiChess exchanged most pieces and queened the passer. It was on time to stop the black passer,the game ended in a tablebase win.

game 24, Seer - KomodoDragon: There were many exchanges after the start, the engines opened the queen side and reduced to a RBN vs RNN position with Seer a pawn up. All pawns were on the king side, there was a lot of shuffling and one pawn exchange. On move 67 Seer captured a second pawn and created a passer, then it gave the rook and queened the passer. Seer gave the queen for two knights and reduced to a tablebase win.

game 25, KomodoDragon - Stockfish: KomodoDragon was a pawn up in a closed position, it seemed to have an advantage until it reduced to a RRN vs RRB position. The pawns stabilized and the engines started to shuffle, extending the 50-move counter with pawn moves and captures. The game was adjudicated on move 174. 

game 26, Ethereal - Seer: There were almost no exchanges after the start, except for one minor piece exchange. On move 29 there was a second minor piece exchange, all pawns were on the board and the king side was blocked. Ethereal had a pawn on a6 and it moved a bishop to b7. The white queen moved forward and the engines reduced to a RRN vs RRB position. There was a very long shuffle, only on move 107 Ethereal pushed a pawn to start opening the queen side. Ethereal gave a pawn and created connected passers, Seer lost the bishop for one. Ethereal captured pawns, then Seer gave its rook for the second passer. The game ended in mate.

Standings after RR1: Stockfish Leela +3, Seer Berserk RubiChess 0, KomodoDragon Ethereal -1, Stoofvlees -4. Stockfish and Leela lead together, both won their games as white and drew as black, the only exception was the draw between them with Leela as white. Stoofvlees lost all its games as black and drew as white. The other 5 engines are close to each other and it is too early to say which of them is stronger than the others. KomodoDragon does not currently look like a natural candidate for third place.

game 34, KomodoDragon - Stoofvlees: The white queen moved forward o the king side, the engines opened the queen side and Stoofvlees kept its king in the center. After a series of exchanges the game reached a RBN vs RR position, the engines continued to trade pawns until there was only one white pawn left. KomodoDragon forced a rook exchange and reduced to a tablebase win. 

game 37, Stockfish - RubiChess: Queens were off early and both engines moved their king without castling. Stockfish had a bishop pair advantage while RubiChess had a passer in the center. Stockfish pushed pawns on the king side, for a long time evals increased slowly without an obvious reason on the board. After move 60 Stockfish managed to get a protected pawn to g7 blocked by the black king. Stockfish exchanged minors and gave a pawn to open the f file, trapping the black king. RubiChess lost material and was mated.

game 38, Leela - Seer: There were a few minor piece exchanges after the start, one pawn exchange opened the f file. The engines exchanged a pair of rooks, Leela gave a pawn and created a passer on the queen side. Seer gave a rook for a bishop for the passer, the game reached a QRB vs QBN position. Seer was a pawn up with a passer on the queen side, it seemed to have a fortress on the king side though evals were high. For almost 30 moves nothing happened other than Leela capturing the black passer, on move 65 Leela gave a pawn and threatened the black king. Seer exchanged minor pieces, its fortress was destroyed. After exchanging queens the white king moved forward, Leela created a passer to win.

game 39, Berserk - KomodoDragon: The engines opened the center and exchanged queens early. The engines mostly shuffled for a while, then reduced to a RRB vs RRN position. Berserk moved both rooks to the 7th rank and the white king moved forward. Berserk captured two pawns and created a passer, then reduced to a rook ending. KomodoDragon couldn't avoid a queening, the game ended in a tablebase win.

game 40, Stoofvlees - Ethereal: The engines blocked the center and opened the b file. After a few piece exchanges Stoofvlees created a passer in the center, the game reached a QBN vs QBN position and the engines shuffled for a long time. On move 63 Stoofvlees exchanged bishops, then it captured a pawn and reduced to a queen ending. The white king moved forward and the engines traded pawns, Ethereal equalized material but Stoofvlees had connected passers in the center. Ethereal delayed with checks but the passers slowly advanced, the game ended in a tablebase win. There were two white wins in this game pair.

game 44, Seer - RubiChess: The engines exchanged minor pieces, the first pawn exchange was on move 21 and Seer went a pawn up. The engines shuffled for a while, then RubiChess regained the pawn and after a series of exchanges reduced to a queen ending. Seer had an advanced passer on the queen side, the white king moved forward for support and the black queen blocked. Seer captured a pawn on the king side, it pushed the passer to the 7th rank and captured a second pawn. RubiChess captured the passer but the game ended in a tablebase win. There were two white wins in this game pair.

game 45, Stockfish - Seer: Seer captured a pawn on the king side, after opening the a file Seer chose not to let Stockfish regain the pawn. Stockfish doubled rooks on the a file and exchanged a pair of rooks, after some preparation it cleared most of the queen side. Seer gave two pawns and opened the h file but there was no real threat on the white king. The game reached a RBN vs RBB position, white with an advanced passer on the queen side. Seer lost a bishop for the passer, Stockfish captured the remaining black pawns and mated.

game 48, Berserk - Stoofvlees: The engines castled in opposite directions, Berserk pushed pawns on the king side and Stoofvlees on the queen side. Berserk captured a pawn on the queen side, it protected its king while creating a passer on the king side. Berserk captured another pawn while Stoofvlees tried to attack the b2 pawn, Berserk gave the passer and reduced to a QRN vs QRB position. After exchanging queens Berserk captured another pawn and the game reached a winning rook ending.

game 52, KomodoDragon - Seer: The center was blocked and there was one pawn exchange after the start. The engines blocked the king side and mostly shuffled, the first piece exchange was on move 45. Seer gave a pawn and opened files on both sides of the board, after a series of exchanges the game reached a QRB vs QRB position. After exchanging queens KomodoDragon captured another pawn and the white king moved forward. Seer lost material, KomodoDragon queened and mated. There were two white wins in this game pair. 

game 53, Stockfish - KomodoDragon: The engines castled in opposite directions quite late in the game, after the pawns advanced the kings had less protections. The engines opened files and reduced to a QRB vs QRN position. Stockfish used the exposed black king to force exchanges of queens and rooks. The white king moved forward and Stockfish captured two pawns. KomodoDragon couldn't stop a queening, the game ended in a tablebase win.

game 56, Leela - Berserk: See featured game below. 

Featured game: Leela - Berserk
game 56

The engines castled in opposite directions, Leela had a bishop pair advantage after Berserk traded both its bishops for knights. Leela's eval jumped very quickly, after exchanging queens on move 18 it was already close to 10.

There was a long period with the engines playing behind their pawns lines, Leela pushed pawns and blocked the king side with one pawn on g6 and the black king in the corner. Then Leela opened the a file and exchanged a pair of rooks. 

Berserk moved its king to the center, Leela exchanged minors and captured the b5 pawn, creating a passer. Leela captured two more pawns, in desperation Berserk gave its knight for a passer. The g6 pawn became an unstoppable passer, Leela queened and reduced to a tablebase win. 

Season 26 league 1 statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins

Final draw rate was 64.4%. 

Game termination

The three most common game termination causes were:
53.4% - TCEC draw rule
21.6% - SyzygyTB
14.0% - Mate

There were 4 crashes in the stage, Clover crashed on time 4 times.

Moves per game

Median= 68.8
Average= 75.1

There were 46 games longer than 100 moves, the longest was 305 moves (Velvet - Viridithas, game 43, draw). 

Time per game (hours)

Median= 1:01
Average= 1:00

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 quickly, 32.6% diverged immediately out of book, 56.8% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 28 plys (Obsidian - Velvet, games 25 and 91, Queen's pawn game, Obsidian won as white) 

Season 26 league 1

Final Standings

Berserk and Seer advance to the premier division. There were 5 engines leading after RR2: Seer, Caissa, Berserk, Obsidian and rofChade. Within this group Berserk drew all games while the other 4 each had one game pair win and one loss. In RR3 rofChade was dropped after losing to Caissa, Arasan and Clover, though it also beat Obsidian. Berserk led by a small margin at that stage after beating Caissa. In RR4 Berserk took over after 5/6 wins as white and one win as black. The other 3 leaders were close to each other, Caissa and Seer drew games as white against lower ranking engines 5 times. In the end all three had the same score, Seer had the advantage in the 3-way tiebreak with a game pair win against Caissa and draws against Obsidian.

Berserk completed the journey from the entrance league to the premier division, though it is not clear yet if it can avoid relegation back to league 1. It was 4th in the premier division of season 24. Obsidian also started at the entrance league and was close to joining Berserk.

The top 5 engines beat the bottom 7 in 41/70 game pairs, rofChade lost two. Clover crashed on time 4 times, strangely all these crashes were in RR2. In 3 cases it was close to losing, once it was in a drawn position.

The two qualifiers will play in the premier division together with Stockfish, Leela, KomodoDragon, RubiChess, Ethereal, Stoofvlees, all played in the premier division of season 24. This season the premier division will be a 4DRR event, without a playoff this season.

Interesting games

game 9, Caissa - rofChade: The engines opened the e file and gradually exchanged pieces, Caissa created a passer on the king side and the game reached a RN vs RN position. rofChade lost two pawns and created a passer on the queen side, while Caissa had a second passer in the center. The white king moved forward and rofChade lost its passer, it lost more material and Caissa queened, followed by mate.

game 17, Igel - Caissa: The center was blocked, the engines exchanged a few minor pieces. Igel placed a protected bishop on d6 and the opened the h file. The white king moved forward and the engines exchanged all rooks, the game reached a QBN vs QNN position. The black king walked to the queen side, Igel gave a knight for two pawns and created connected passers in the center. Caissa lost a knight for one passer, then it lost more material and was mated.

game 23, Revenge - Clover: Revenge pushed pawns on the king side and castled long, there were only a few exchanges after the start and the engines mostly shuffled. On move 39 Revenge captured a pawn and created a passer on the queen side, on move 61 the queens were exchanged. The game reached a RN vs RB position, Clover captured the white passer but Revenge captured a pawn and created a passer on the king side. Clover couldn't prevent a queening and was mated.

game 25, Obsidian - Velvet: The engines opened the center and there were many exchanges, the game reached a RBN vs RBN position with white a pawn up. Obsidian had a pawn majority on the queen side, the white king moved forward to support the pawns. The engines traded pawns and minor pieces, Obsidian created a passer on the queen side. The game ended in a tablebase win.

game 27, rofChade - Revenge: Material was equal but the black pieces had only a little space to move, and rofChade placed a knight on b6. On move 39 rofChade gave a rook for a knight and pawn, creating a passer on the queen side. Revenge gave the material back and the game reached a QRB vs QRB position. After exchanging queens Revenge lost the rook for the passer, the game ended in a tablebase win.

game 36, Obsidian - Clover: Clover gave a knight for two pawns, then a rook for a bishop. The white king was under attack and Obsidian had a trapped knight. Obsidian freed its knight, then gave back a rook for a knight. It surrounded its king with pieces, after exchanging queens the game reached a RBN vs RB position. Both engines pushed a passer forward, eventually both passers were captured. The white king moved forward and Clover lost its remaining pawns. Clover lost more material and Obsidian queened a passer followed by mate.

game 39, Igel - Arasan: The engines castled in opposite directions, Igel captured a pawn. The engines opened both sides of the board, Igel captured a second pawn while Arasan tried to attack on the queen side. Igel reduced to a QN vs QB position and pushed a passer to the 7th rank. Arasan lost its queen for the passer and was mated.

game 40, Seer - Revenge: Revenge gave a pawn early, the engines gradually exchanged pieces until only RNN vs RBB were left. Seer had a pawn majority on the queen side. Seer first pushed a pawn forward on the king side and created a passer, then pushed pawns on the queen side. Revenge gave a bishop and captured the white passers, Seer had enough material advantage to reduce to a tablebase win.

game 46, Arasan - Seer: There were many exchanges after the start and the game reached a RBN vs RBN position with white a pawn up. Arasan had a passer in the center and a pawn majority on the queen side while Seer had a passer on the king side. Arasan captured another pawn and its king moved forward on the queen side. Arasan pushed a passer to the 7th rank, Seer lost a knight for a pawn but couldn't prevent a queening. The game ended in mate.

game 51, Seer - Obsidian: Obsidian moved its king forward in the center instead of castling. There was a long period of mostly shuffling, Seer moved its king back to the center as well and on move 37 Seer opened the h file. Obsidian opened the center and the white king moved to the queen side. Seer moved a rook to the 7th rank and the black king also walked to the queen side. Seer captured a knight and the game reached a QB vs Q position, then Seer reduced to a won king and pawns ending. 

game 53, Caissa - Revenge: Revenge was a pawn up but its king was vulnerable in the center. Caissa gave a knight for two pawns and opened the center, then it gave a rook for a bishop but captured teh black queen for another rook. The game reached a QB vs RRN position, after some shuffling Caissa captured two pawns and created connected passers on the queen side. The white king moved forward, eventually Caissa queened and forced mate.

game 60, rofChade - Igel: There were no exchanges until move 26, then a series of pawn and minor piece exchanges exposed the black king. The game reached a RBB vs RBN position, Igel captured a pawn but rofChade created a passer. rofChade capured the bishop for the passer, the game ended in a tablebase win.

game 64, Caissa - Obsidian: Obsidian castled long and Caissa opened the queen side and exposed the black king. Caissa avoided exchanging queens and the game reached a QRB vs QRB position. Caissa captured a pawn and placed its major pieces on the back rank, Obsidian lost material and was eventually mated.

Standings after RR1: Igel Caissa +3, Seer Berserk +2, Obsidian Arasan rofChade +1, Clover Velvet Revenge Viridithas -2, Minic -5. There are 7 engines with a positive score, it is likely that the two qualifiers will be in this group. Only Berserk has no losses so far, but it has only two wins against lower ranking engines. Caissa beat Obsidian and rofChade but lost to Igel. The picture will be clearer after the reverse games.

game 72, Seer - Igel: Igel was a pawn up from the start, Seer captured two pawns and exchanged queens. Seer focused on the queen side, it traded pawns and went two pawns up with two passers. The game reached a RB vs RB position, after exchanging rooks Seer pushed its passers. The bishops had opposite color but the black king was too far away to help, Seer had a passer on the 7th rank and it managed to reduce to a tablebase win.

game 75, rofChade - Caissa: rofChade created a central passer after a knight exchange. The engines cleared the queen side pawns and rofChade was a pawn up with only rooks and bishops left. The engines exchanged a pair of rooks and after some shuffling the other pair as well. rofChade captured a second pawn, then gave a pawn to created connected passers. Caissa lost a bishop to capture the passers, the game ended in a tablebase win.

game 79, Velvet - Arasan: There were many exchanges after the start and the game reached an opposite color bishop ending with white a pawn up. The white king moved forward, somewhere Arasan played inaccurately and after 40 moves Velvet managed to capture another pawn and create a passer. After another shuffle the engines traded pawns, eventually Velvet had 3 passers and Arasan couldn't stop them all. The game ended in a tablebase win.

game 83, Caissa - Igel: Igel castled long and Caissa created half open files on the queen side using exchanges. Caissa gave a pawn and created a passer in the center, Igel gave a rook for a bishop to captured the passer. The game reached a QRR vs QRN position, Igel was a pawn up but Caissa regained the pawn and exchanged queens. The white king moved forward on the king side, Caissa captured more pawns. Igel lost more material, Caissa queened a passer and mated.

game 86, Seer - Caissa: Caissa captured a pawn on the queen side, Seer opened the king side and exchanged a few minor pieces. After some shuffling Seer regained the pawn and moved its queen forward on the king side, Caissa exchanged queens and eventually the game reached a RN vs RB position. Material was equal but most of the black pawns were on squares of the wrong color and the bishop couldn't protect them. The white king moved forward and Seer created a passer. After exchanging minors Seer went a pawn up, the game ended in a tablebase win.

game 93, Revenge - rofChade: Revenge captured a pawn and created a passer on the queen side. The engines gradually exchanged pieces and the game reached a RRN vs RRN position. Revenge exchanged a pair of rooks and slowly pushed the passer to the 7th rank. rofChade managed to capture the passer, but then Revenge the remaining black pawns and created connected passers on the king side. Revenge queened a passer and mated.

game 101, rofChade - Arasan: rofChade was a pawn up with a passer on the queen side from the start. Arasan gave another pawn and exchanged queens, the engines shuffled for a long time. On move 53 the engines started to exchange pieces and pawns, Arasan captured the passer and the game reached a rook ending. The black king was pushed to the back rank and was in danger, rofChade used this to capture two pawns, then queen a passer and mate.

game 104, Obsidian - rofChade: There were many exchanges after the start and the game reached a QRB vs QRB position. rofChade overlooked something and allowed Obsidian to capture a pawn and create a passer. After exchanging bishops Obsidian connected a second passer and pushed them forward. After queens were exchanged the passers were unstoppable, Obsidian queened and mated.

game 112, Seer - Arasan: The engines castled in opposite directions, Seer pushed pawns on the king side. While Arasan freed a trapped bishop from the corner Seer created a passer in the center on the 7th rank. Seer captured a rook for a bishop,vthe game reached a QRR vs QRB position. Arasan tried to avoid exchanging queens but eventually Seer forced the exchange. Seer pushed another passer, Arasan lost material and the game ended in a tablebase win.

game 117, Obsidian - Seer: The white queen moved forward and captured a pawn on the king side, the black king stayed uncastled in the center. Seer regained the pawn, there were many exchanges and the game reached a RRB vs RRB position. The engines continued to trade pawns and rooks, leading to an opposite color bishop ending. Material was equal but white had a better pawn structure. Obsidian managed to create connected passers on the queen side supported by the king. Seer couldn't prevent a queening and was mated.

game 128, rofChade - Seer: Queens were off early and Seer moved its king without castling. rofChade moved its king as well, the engines exchanged pieces until only RBN vs RBN remained. Not a lot happened until Seer decided to exchange rooks on move 39. rofChade captured a pawn and then created a passer in the center. While Seer blocked the white passer rofChade managed to capture a second pawn, then gave a pawn back and created a second passer. Seer lost its bishop for a passer, rofChade queened and mated.

game 129, Clover - Berserk: The engines castled in opposite ditrections and opened the f file. Berserk pushed a pawn to g6 yet Clover kept its king safe. Clover created a passer in the center, the engines gradually exchanged pieces. Clover captured the g6 pawn, on move 54 the game reached a RNN vs RNN position. Clover created another passer on the king side and the white king moved forward. Progress was slow, Clover kept the black king away and aftere exchanging a pair of knights it pushed its passer slowly. Berserk lost material, Clover queened and the game ended in a tablebase win.

Standings after RR2: Seer Caissa +5, Berserk Obsidian +4, rofChade +3, Igel +1, Viridithas -1, Arasan Revenge -2, Velvet -4, Clover -5, Minic -8. At the half way point there are 5 engines close to the top. Seer and Caissa both have 6 game pair wins and one loss, Seer beat Caissa and rofChade beat Seer. Berserk has no game pair losses but only 4 wins, Obsidian has 5 wins and one loss to Caissa. rofChade has 1 loss to Obsidian and 4 wins. Igel also has a positive score but it drifted away from the leaders. Arasan is far from the leaders after 2 game pair losses and no win in the reverse games. For some reason Clover crashed 4 times on time in RR2, in three games it was close to losing anyway - perhaps its was of resigning. It crashed once in a drawn position against Viridithas. 

game 140, Berserk - Igel: The engines exchanged minor pieces and Berserk created a passer in the center through such an exchange. After some shuffling Igel created a passer on the queen side and the game reached a QRR vs QRR position. Berserk captured two pawns and protected its passer, the engines exchanged a pair of rooks. After Berserk captured the black passer it pushed its own passer forward, Igel exchanged queens but it was mated on the back rank.

game 141, Caissa - rofChade: There were a few pawns exchanges after the start, the first minor piece exchange was on move 24. Caissa captured a pawn, it moved both its knights to the queen side where they were very effective together with two pawns. rofChade gave another pawn and the game reached a QNN vs QBN position. The black queen tried to attack but was too weak and Caissa found safety for its king. Caissa captured another pawn and created passers, then forced a queen exchange. rofChade lost its pieces for passers, Caissa queened and mated.

game 162, Berserk - Caissa: Caissa castled short despite the fact that its g pawn was gone. The black queen captured a pawn on the queen side, Berserk moved its major pieces forward and Caissa manually uncastled its king. The engines exchanged pieces until only RRN vs RRN remained, Berserk captured pawns until it was two pawns up. The engines reduced to a rook ending and the game ended in a tablebase win.

game 165, Minic - Seer: The center was blocked, Seer equalized quickly. Minic opened the queen side and tried to attack, Seer gave a bishop for a pawn and opened the king side. Minic captured a rook for a bishop, the game reached a QRR vs QRN position with black two pawns up. Seer ethreatned the white king on the g file and created a passer on the queen side. Minic exchanged queens and blocked the passer on the 2nd rank. Minic captured the passer and Seer created another, the black king moved forward and the white king couldn't help. Minic lost material and the game ended in a tablebase win. 

game 167, Arasan - rofChade: The engines castled in opposite directions and the center was blocked. Arasan gave a bishop for a pawn and opened the king side, rofChade opened the queen side. Arasan gave a rook for a bishop and pawn attacked the black king. rofChade gave back the material and the game reached a RN vs RB position. The white knight was much more effective, Arasan quickly captured two pawns, it had two doubled pawns but one pair were passers. The white king moved forward, Arasan captured more pawns and created another passer. Arasan queened and mated.

game 170, rofChade - Obsidian: rofChade pushed pawns on the king side and captured a pawn, leaving its king a little exposed. Obsidian was not able to take advantage of this weakness though both its knights were active on the king side. After some shuffling Obsidian gave a rook for a knight, this created a passer and opened the queen side. rofChade also created a passer and pushed it to the 7th rank. The game reached a QRR vs QRN position, Obsidian gave a rook in a desperate attack on the white king. rofChade queened the passer, exchanged a pair of queens and mated.

game 180, Clover - rofChade: The engines castled in opposite directions, after a few minor piece exchanges the king side opened and Clover captured a pawn. The game reached a RB vs RB position, Clover had a pawn majority on the king side. rofChade tried to protect its pawns but eventually Clover captured a pawn and created connected passers. Clover slowly pushed the passers with the king's support, rofChade lost the rook for a passer and the game ended in a tablebase win.

Standings after RR3: Berserk +8, Obsidian Seer Caissa +7, Igel rofChade +2, Viridithas 0, Arasan -2, Revenge -5, Velvet -6, Clover -7, Minic -13. The leader pack is down to 4 engines, rofChade was dropped after a weak RR that included losses to Arasan and Clover. Berserk has a small lead at the top, its results in RR3 were better than in RR1 with wins against Caissa and Igel. Obsidian, Caissa and Seer had similar results in RR3 as in RR1. Caissa beat rofChade and Obsidian lost to rofChade, the remaining wins were in games against lower ranking engines. Seer is still in joint second place due to an unexpected win over Minic, in black against the bias. The reverse games will determine which 2 engines will advance to the premier division. 

game 203, Berserk - rofChade: Berserk opened the king side and exposed the black king. After a series of exchanges the game reached a QR vs QBN position with white two pawns up. Berserk had connected passers on the king side, after some checks and some shuffling the engines exchanged queens. Berserk captured the remaining black pawns and slowly pushed its passers. The game ended in a tablebase win.

game 215, Caissa - Igel: The engines castled in opposite directions, Caissa attacked on the king side and Igel exchanged queens. The game reached a RBN vs RNN position, material was equal but Caissa had a passer on the king side. The white king crossed the board and moved forward to support the passer. Caissa moved a rook to the 7th rank, while Igel was busy defending on the king side Caissa captured two pawns on the queen side. Igel lost material and was mated.

game 216, Berserk - Seer: There were almost no exchanges after the start, Berserk pushed pawns on the queen side. On move 27 Berserk gave a rook for a bishop, then the engines shuffled for a long time. After move 61 a few exchanges opened a file on the queen side, the engines exchanged a pair of rooks and then opened the king side. The black king was in danger, and Berserk pushed a passer to the 7th rank on the queen side as well. Seer captured the passer but in a series of exchanges lost material and the game reached a BBN vs N position. The game ended in mate.

game 225, Revenge - rofChade: Queens were off early and the black king moved and blocked the queen side rook. The white king stayed in the center but its rooks were free. The engines exchanged a pair of rooks, Revenge gave a pawn to create a passer on the king side while giving rofChade connected passers there. However, the game reached a RBN vs RBN position and Revenge captured two pawns on the queen side, creating another passer there. rofChade lost its knight for a passer, it managed to push a passer to the 2nd rank but there it was stopped. Revenge trapped the black king and mated.

Standings with 5 rounds to go: Berserk +12, Obsidian +9, Caissa +8, Seer +7, rofChade Igel +2, Viridithas -1, Arasan Revenge -5, Clover -7, Velvet -8, Minic -14. Berserk broke away from the other engines, it beat Seer and rofChade and is comfortably in the lead. Obsidian's results were as expected with two wins as white against lower ranking engines. Both Caissa and Seer drew a few games they needed to win, they need to do better in order to have a chance of advancing.

game 239, Minic - Berserk: The engines castled in opposite directions, there were only a few exchanges after the start. Berserk equalized, then opened the queen side. Minic countered with a knight sacrifice to open the king side, it placed all its major pieces on the h file. Berserk kept its king safe, after some shuffling the engines exchanged a pair of rooks. Berserk shifted to attack the white king, it captured pawns and reduced to a QBB vs QB position. Minic was still a pawn up but Berserk managed to exchange pieces and reduce to a tablebase win.

game 240, Viridithas - Caissa: Both engines castled long, Caissa was a pawn up but Viridithas developed its pieces faster. Caissa gave the pawn back, after a series of exchanges the game reached a QRB vs QRB position. Viridithas captured two pawns and created a passer on the king side. Caissa gave a rook for a bishop and captured back two pawns. Caissa avoided exchanging queens but lost its bishop for the passer. Caissa delayed with checks but eventually the game ended in a tablebase win.

Standings with 2 rounds to go: Berserk +13, Obsidian +9, Caissa Seer +8, rofChade+2, Igel Viridithas +1, Revenge -5, Arasan Clover -6, Velvet -9, Minic -16. Obsidian kept its small lead in second place, Seer and Caissa are still close. Caissa nearly caught up to Obsidian but lost unexpectedly to Viridithas, Seer improved its score a little and is in joint third place. Obsidian still has to face Berserk and Caissa, while Caissa and Seer both have a game as white against lower ranking engines. We may see a tiebreak for second place, currently Seer has a game pair win against Caissa and Caissa has a game pair win against Obsidian. 

game 256, Berserk - Obsidian: Both engines castled long and both queens moved forward. Both engines pushed pawns forward, Obsidian opened the g file and Berserk opened the c file. The white king was more exposed but Berserk was the one attacking. Berserk captured a rook for a bishop and two pawns, the game reached a QR vs QB position. Berserk used checks to capture pawns while Obsidian gave checks to delay when possible. With white a pawn up the queens were exchanged, Berserk queened a passer and mated.

Caissa and Seer drew as white against Arasan and Clover. Together with Obsidian's loss the three engines are tied at +8 with one round to go. Seer has the tiebreak advantage under these conditions.

In the last round Seer drew as black against rofChade. Obsidian had one last chance against Caissa but this game also ended in a draw. No change in the standings at the top, Seer finishes in second place on a triple tiebreak with Obsidian and Caissa.

Season 26 league 2 statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins

Final draw rate was 63.3%. 

Game termination

The three most common game termination causes were:
51.1% - TCEC draw rule
29.5% - SyzygyTB
12.9% - Mate

There were no crashes in the stage.

Moves per game

Median= 66.3
Average= 74.6

There were 43 games longer than 100 moves, the longest was 286 moves (BlackMarlin - Obsidian, game 39, Obsidian won). 

Time per game (hours)

Median= 1:02
Average= 1:00

Openings

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

The engines had very little freedom to choose the opening variant, 98.5% of the game pairs (all but 2) repeated the same ECO code and 97.7% (all but 3) repeated the opening variant twice. In all of the game pairs the first letter of the ECO code was repeated.

Reverse pairs, wins

Reverse pairs, same moves

Pairs of reverse games diverged quickly, 27.3% diverged immediately out of book, 62.1% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 17 plys (Marvin - Uralochka, games 11 and 77, Alekhine's defence, modern variation, Uralochka won as white) 

Season 26 league 2

Final standings

Berserk, Obsidian, Viridithas, Velvet and Arasan advance to league 1. Berserk and Obsidian lead from the start and only increased their lead. Berserk beat all other engines without a single loss, it won 18/22 game pairs. Obsidian lost twice to Berserk and once to Viridithas but won almost all other game pairs, only ScorpioNN held it to a draw in two game pairs. 

The race for the other 3 qualifying spots involved several engines and continued until the final rounds. After the first DRR Viridithas had a small lead in third place with at least 5 engines fighting for two more spots. After the third RR Viridithas, Velvet and Arasan were together in third place with Stormphrax and Uralochka chasing. This group of 3 engines kept their lead in the fourth RR, ensuring their qualification in the final two rounds.

The five qualifiers will play in league 1 together with:
played in season 25 premier division: Igel
played in season 25 league 1: rofChade, Clover, Seer, Caissa, Revenge, Minic

Interesting games

game 7, Arasan - ScorpioNN: The black king was stuck in the center with both sides unsafe. Arasan gave a pawn and threatened to open the center. ScorpioNN traded pieces and reduced to a Q vs R position, which then took Arasan more than 30 moves to reach a tablebase win.

game 10, Berserk - Viridithas: Berserk was up a pawn from the start, the engines exchanged pieces until only QRN vs QRN were left. After some shuffling Viridithas started to play inaccurately, it cpatured white pawns but Berserk attacked the black king. After exchanging queens Berserk captured pawns until it was two pawns up, then slowly pushed a passer forward to win.

game 13, Obsidian - Arasan: The engines opened files on both sides and exchanged pieces until only QRB vs QRN were left. Arasan had a passer but it gave a pawn to defend its king, creating connected passers for Obsidian. After exchanging queens Obsidian managed to capture the remaining black pawns and the game ended in a tablebase win.

game 14, Uralochka - Ginkgo: Uralochka had a bishop pair advantage, the engines mostly shuffled behind their pawn lines for a long time though evals increased slowly. On move 46 the engines opened a file on the queen side and reduced to a BB vs NN position. Uralochka's bishops were strong, it used them to reduce to a winning B vs N ending 3 pawns up.

game 24, Obsidian - Uralochka: The engines opened the queen side, then slowly exchanged pieces until the game reached a BN vs BB position with white a pawn up. Afte r some shuffling the engines reduced to an opposite bishops ending and Obsidian captured a second pawn. Uralochka wasn't careful enough, Obsidian managed to move its king forward and created connected passers to win.

game 26, Viridithas - Obsidian: Queens were off early, the black king moved forward in the center. Viridithas opened the center and captured a pawn, the game reached a double rook ending. OBsidian pushed a passer forward, then gave its two rooks and queened the passer. Viridithas managed to capture all the black pawns and its 3 pawn advantage was enough to win. 

game 39, BlackMarlin - Obsidian: The game reached a RRN vs RRN position, all pawns were on the board and the engines shuffled for a long time. On move 103 BlackMarlin gave a pawn, on move 158 Obsidian pushed a pawn, then it captured a second pawn and created a passer. On move 196 Obsidian pushed the passer, then BlackMarlin blundered and gave a rook for a knight and pawn. Obsidian now had connected passers, after another long shuffle Obsidian gave a pawn and opened a file. The engines traded pawns and Obsidian reduced to a winning rook ending.

game 48, Viridithas - Stormphrax: There were a few exchanges after the start and the engines mostly shuffled behind their pawn lines. Both kings moved to the king side, the white king side rook developed through the h file, while the black king side rook passively defended g7.On move 46 Viridithas created a passer after an inaccuracy by Stormphrax, then it gave a pawn and opened the queen side. Both engines pushed passers, Stormphrax developed its trapped rook. Eventually all passers were captured and the game reached a QR vs QN position. Viridithas pinned the black knight and then captured it for a pawn, the game ended in a tablebase win. 

game 58, Uralochka - Velvet: The engines opened files on both sides, Uralocjka placed a knight on h6 and the black king ran to the center for safety. The game reached a QRN vs QRN position, Velvet gave a pawn to move the strong knight, Uralochka exchanged rooks and created a passer on the queen side. Velvet capture the passer and lost its knight, the game ended in a tablebase win.

game 63, Velvet - Viridithas: The engines opened the g file and blocked the center. Velvet walked its king to the queen side, gave a pawn and attacked the king side. Viridithas captured another pawn but its pieces were too far to help its king. Velvet traded pieces and gave pawns, but eventually it was mated.

game 64, DeepSjeng - Uralochka: DeepSjeng captured a pawn and created a passer on the queen side. Then it gave a knight for a pawn on the king side and pushed the passer forward. Uralochka lost a rook for the passer and the game reached a QRB vs QBN position. It took DeepSjeng some time to find a way to improve, after trading pawns the engines exchanged queens. DeepSjeng pushed pawns forward, trapped the black king and mated.

game 65, Berserk - Obsidian: Berserk pushed pawns on the king side, its king had no pawn support. The engines opened the queen side and traded a pair of pawns. Berserk controlled the b file, the black queen moved forward but could not attack on its own. Berserk exchanged the remaining rooks and attacked the black king, Obsidian lost a knight so its queen could get back. The game reached a QN vs Q ending, Obsidian lost the queen for a passer and was mated.

Standings after RR1: Obsidian Berserk +4, Viridithas Arasan +2, Uralochka +1, Ginkgo ScorpioNN Stormphrax Velvet -1, DeepSjeng -2 Marvin -3, BlackMarlin -4. Obsidian and Berserk are leading. Berserk has no loss and winning all games as white except one against Velvet, including a win against Obsidian. Obsidian has another loss against Viridithas, and a win as black against BlackMarlin. Viridithas, Arasan and Uralochka are in the race for two more qualifying spots.

game 69, Berserk - Uralochka: The engines opened the queen side, Berserk moved its rooks forward and Uralochka pushed a passer to the 3rd rank. Berserk captured the passer and another pawn, then gave a rook for a bishop and opened the king side. Uralochka gave back material to save its king, the game reached a RNN vs RBN position with white 3 pawns up. Berserk gained more material and mated.

game 71, Velvet - Stormphrax: There were only a few exchanges after the start, a few pawn exchnages opened the board and Velvet had a bishop pair advantage, both engines had a passer in the center. Velvet gave a rook for a knight and pawn, creating a passer on the queen side supported by its bishops. The game reached a RBB vs RRN position, Velvet then regained the material with a bishop fork. Velvet went two pawns up, Stormphrax lost the rook for a passer and the game ended just before mate.

game 80, Ginkgo - Uralochka: Ginkgo moved its queen forward and cleared the black pawns on the queen side. Then it gave a bishop and captured the remaining black pawns. Uralochka traded RR for Q and reduced to a Q vs RRB position with white 4 pawns up. It took Ginkgo many moves to push its pawns forward with its king support, but eventually Uralochka lost material and was mated.

game 85, Velvet - Arasan: Velvet created a passer in the center, the engines exchanged pieces and Velvet traded two minor pieces for a rook. The game reached a QR vs QBN position, Velvet created a second passer on the king side. After exchanging queens Arasan captured one passer but started to lose material. The game ended in a tablebase win.

game 107, Marvin - Velvet: The engines castled in opposite directions and pushed pawns facing the opponent's king. The game reached a RBN vs RBN position and Marvin went a pawn up. Both engines had a passer, after exchanging bishops and a pair of pawns Marvin connected a second passer. The game ended in a tablebase win.

game 109, Berserk - Arasan: Berserk gave 3 pawns and started a series of exchanges that resulted in a RRN vs Q imbalance. Arasan created two passers but its queen was a target for the white pieces, Berserk eventually got two pawns back. The black king was exposed, Berserk moved its pieces forward and Arasan lost material but couldn't avoid mate. 

game 117, Uralochka - ScorpioNN: There were many early exchanges and the game reached a RBN vs RBN position with white a pawn up. After exchanging rooks both engines had a passer, it seems ScorpioNN was not accurate and evals started to increase. ScorpioNN reduced to an opposite color bishop ending, and even equalized material but Uralochka had connected passers that could not be stopped. The game ended in a tablebase win.

game 124, Velvet - Uralochka: Velvet captured an early pawn, the engines opened the king side and Uralochka exchanged queens. In a series of exchanges Uralochka gave a knight for pawns and the game reached a BBN vs BB position with black 2 pawns up. Uralochka pushed passes on the queen side, after trading minor pieces it took Velvet a long time to find the way forward. Eventually the last white pawn became an unstoppable passer, Velvet queened and mated.

game 125, ScorpioNN - Viridithas: Both engines castled long, Viridithas traded both its bishops for knights. ScorpioNN captured a pawn and created a passer on the queen side, then exchanged queens. The game reached a RBB vs RNN position, Viridithas captured the white passer but ScorpioNN went two pawns up and created connected passers on the king side. Viridithas lost a piece for the passers, the game ended in a tablebase win. 

game 129, Viridithas - Velvet: Queens were off early and Viridithas went a pawn up. Velvet gave a rook for a bishop and pawn, cleared the white pawns on the queen side and created two passers. Viridithas created a passer on the king side in a RRN vs RBB position, it captured one passer and gave back the exchange. Velvet captured a passer but lost its bishop for another, the game ended in a tablebase win.

Standings after RR2: Berserk +9, Obsidian +6, Viridithas +3, Arasan +1, Velvet Uralochka 0, Stormphrax Ginkgo -1, ScorpioNN DeepSjeng -2, Marvin -5, BlackMarlin -8. Berserk and Obsidian increased their lead at the top, Berserk won 9/11 game pairs without loss ,Obsidian won 7/11 with two losses. Viridithas has a small lead in third place, fourth place is still very much contested. It appears that there are 5 qualifying spots at this stage, all engines have a chance other than Marvin and Blackmarlin.

game 137, Stormphrax - Velvet: Stormphrax went a pawn up, then the engines gradually exchanged pieces until the game reached a rook ending. Stormphrax had a passer in the center, it king moved forward to support it. The engines traded pawns, the game ended in a tablebase win.

game 142, Berserk - Viridithas: Berserk was a pawn down and its king had to move without castling, but it managed to capture a rook for a knight and the game reached a RRB vs RNN position. Both white rooks moved to the 7th rank, Viridithas exchanged rooks and Berserk captured all black pawns. Berserk had one pawn left, the engines continued playing a 7-man winning position for 20 more moves before adjudication.

game 145, Obsidian - Arasan: There were many exchanges after the start, the engines reduced to a RN vs R ending with black two pawns up with connected passers. Arasan was not accurate and Obsidian managed to capture one of the passers, then rook were exchanged. The game ended in a tablebase win.

game 156, Obsidian - Uralochka: Uralochka started a series of exchanges that ended in a RB vs Q position with white 3 pawns up. Both engines created passers and pushed them forward, Uralochka gave its queen for the white passer but queened its own passer. Obsidian pushed another passer slowly, there was a lot of shuffling but close to the 50 move draw Obsidian found the winning path. It gave its passer and captured the last black pawn, the black king became trapped and was mated.

game 159, Stormphrax - Ginkgo: The game reached a RB vs RB position with white a pawn up. Stormphrax had a pawn majority on the queen side, it attacked the black pawns on the king side and captured a second pawn. Ginkgo captured a pawn on the queen side but Stormphrax created connected passers on the king side to win.

game 164, Berserk - Velvet: Berserk captured a pawn, Queens were off early and the engines castled in opposite directions. The engines played with caution, Berserk created a passer in the center. Velvet lost a knight to capture the passer, the engines traded pawns until each had one pawn left. A series of exchanges reduced to a BN vs B position and the game ended in a tablebase win.

game 167, Obsidian - Stormphrax: Obsidian captured a pawn, the engines gradually exchanged pieces in a closed position. The game reached a BN vs BN position, Obsidian captured a second pawn and created a passer on the queen side. Stormphrax tried to block the board, all pawns were inaccessible to the bishops. It took Obsidian a long time but eventually it created a second passer and its king moved forward. Stormphrax lost material and the game ended in a tablebase win.

game 195, Velvet - Viridithas: Velvet pushed a pawn to h6 and castled long. The engines exchanged pieces and pawns, Viridithas captured the h6 pawn but the game reached a RB vs RN position with white a pawn up. Viridithas captured a passer and Velvet captured another pawn and created another passer. Velvet gave both pieces to queen the passer, then queened again and won.

game 196, DeepSjeng - Uralochka: The engines blocked the center and played behind their pawn lines, on move 32 DeepSjeng opened the king side and threatened the black king. Uralochka gave a rook for a knight, the engines exchanged pieces until only RR vs RB remained. DeepSjeng eventually created a passer and pushed it to the 7th rank. Uralochka traded rooks to capture the passer, in the R vs B ending DeepSjeng created connected passers, queened and mated.

game 197, Berserk - Obsidian: Obsidian went a pawn up and created doubled passers in the center. The engines shuffled and exchanged minor pieces, on move 63 the engines exchanged all rooks and reduced to a QBB vs QBN position. Berserk created a passer in the center, regained the pawn and exchanged queens. Obsidian lost the knight to capture the passer, Berserk slowly captured the remaining black pawns and the game ended in a tablebase win.

Standings after RR3: Berserk +14, Obsidian +9, Viridithas Arasan Velvet +2, Stormphrax +1, Uralochka 0, Ginkgo DeepSjeng -2, ScorpioNN -5, BlackMarlin -10, Marvin -11. Berserk and Obsidian increased their lead again, they will finish in the top two places. There are 5 engines fighting for the remaining 3 qualifying spots. Decisive games within this group may have dramatic effects on the final standings.

game 202, DeepSjeng - Viridithas: DeepSjeng had an advantage in a RB vs BN position, but only shuffled and couldn't find a way to win. After 50 moves it gave up the bishop and the game was adjudicated.

game 203, Velvet - Stormphrax: There were a few exchanges after the start, on move 32 Velvet gave a pawn and started to open the position. After a series of exchanges almost all pieces were gone and only BN vs B were left with black a pawn up. It took Velvet more than 30 moves to capture all the black pawns, the game ended in a tablebase win.

game 206, BlackMarlin - Velvet: There were almost no exchanges after the start, on move 34 BlackMarlin went a pawn up, the first piece exchange was on move 39. The engines gradually cleared the pieces from the board, on move 60 the game reached a same color bishops ending. BlackMarlin captured two more pawns and exchanged bishops, then queened a pawn and mated.

game 214, Berserk - Stormphrax: The center was blocked with most pieces on the king side. Berserk captured a pawn and created a passer on the queen side, while threatening the black king on th eking side. Stormphrax blocked the passer, Berserk captured a second pawn and reduced to a RRN vs RRN position. Stormphrax had to cover more passers, Berserk exchanged a pair of rooks and captured the remaining black pawns. The game ended in a tablebase win. 

game 217, Velvet - Arasan: Arasan gave a pawn early, there were a few minor pieces trades. Then in a series of exchanges the engines reduced to a queen ending. Velvet created a passer, then got its king to a safe square. Arasan couldn't prevent a queening and was mated.

game 224, Obsidian - Viridithas: Viridithas captured a rook for a bishop, then gave back the exchange to get rid of a strong knight. The engines reduced to a BB vs BN position, Obsidian had a pawn majority on the king side and Viridithas gave a knight for two pawns to avoid a queening. Viridithas lost its bishop for the last white pawn, the game ended in a tablebase win.

game 234, Viridithas - Uralochka: Viridithas captured a pawn early, it had a pawn majority on the queen side. Uralochka opened the f file and placed its major pieces there. Viridithas created a passer on the queen side and pushed it to the 7th rank. There was some shuffling and Uralochka regained the pawn, then in a series of exchanges Uralochka got rid of the passer but lost a piece. The game reached a QRB vs QR position, Viridithas captured a pawn and the game ended in a tablebase win.

Standings with 5 rounds to go: Berserk +16, Obsidian +10, Velvet +3, Viridithas +2, Arasan +1, Uralochka Stormphrax 0, DeepSjeng -1, Ginkgo -2, ScorpioNN -6, BlackMarlin -10, Marvin -13. Velvet has a small lead in third place after beating Arasan and Stormphrax, though it lost to BlackMarlin. Viridithas in fourth also has good chances of advancing after beating Uralochka. A lot can still change in the last rounds.

game 241, Berserk - Arasan: The engines opened the queen side and Berserk captured a pawn. Arasan regained the pawn and the engines continued to exchange pieces until only RBB vs RBN remained. After some shuffling the engines traded bishops and cleared the queen side pawns. Berserk managed to capture all the black pawns and forced mate.

game 245, BlackMarlin - Uralochka: The engines castled in opposite directions, BlackMarlin opened the king side, Uralochka gave a rook for a knight and reduced to a RRN vs RBN position. Uralochka was a pawn up with connected passers on the king side, BlackMarlin captured a pawn and created a pawn majority on the queen side. BlackMarlin managed to capture the black passers for a knight and the game reached a R vs BN position with white two pawns up. BlackMarlin captured pawns and gave its rook for a bishop, Uralochka couldn't stop the white passers and was mated.

game 247, Arasan - Stormphrax: The engines traded Q for RB, Stormphrax thought it was fine for a long time. The black king had weak pawn support, the white rooks controlled the center. Stormphrax tried to attack with a rook sacrifice, after Arasan found safety for its king it gained more material and mated.

game 250, Obsidian - Velvet: The black queen moved forward early, both kings moved without castling. Velvet captured a pawn but its king and queen were exposed to attacks. Obsidian moved both rooks to the 7th rank, Velvet gave its queen and two pawns for the two rooks. The black king was still under threat, Velvet countered with its rooks against the white king. Eventually Velvet gave a rook for a bishop and reduced to a Q vs RN ending. Obsidian was two pawns up, it created connected passers and the game ended in a tablebase win.

Standings with 2 rounds to go: Berserk +17, Obsidian +12, Viridithas +3, Velvet +2, Arasan +1, Uralochka Stormphrax Ginkgo -1, DeepSjeng -2, ScorpioNN -6, BlackMarlin -11, Marvin -13. After their losses Uralochka and Stormphrax are close to being out of the race. Ginkgo is also only a point away from 5th place. However, with only two rounds left it is very likely that Arasan, Velvet and Viridithas will join the two leaders to qualify.

In round 43 all games were drawn except one, Berserk beat Ginkgo. As a result Viridithas and Velvet are safe, Ginkgo is out, Arasan still has a one point lead over Uralochka and Stormphrax.

In the last round Arasan drew and ensured 5th place. Uralochka won its last game but this only reduced the gap and was not enough to close it.