Season 23 premier division statistics

A summary statistics table of previous stages and seasons.  

Draw rate, wins

Final draw rate was 57.1%. 

Game termination

The three most common game termination causes were:

45.1% - TCEC draw rule
23.2% - SyzygyTB
20.5% - Mate

There were no crashes in the stage.

Moves per game

Median= 69.25
Average= 78.1

There were 38 games longer than 100 moves, the longest was 279 moves (rofChade - Stockfish, game 206, draw). 

Time per game (hours)

Median= 2:05
Average= 2:02

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, only 1.79% of the game pairs (=2 game pairs) did not repeat the same opening variant twice.

Reverse pairs, wins

Reverse pairs, same moves

Most of the pairs of reverse games diverged quickly, 23.2% diverged immediately out of book, 52.7% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 33 plys (Ethereal - KomodoDragon, games 135 and 163, QGD Slav, Tolush-Geller gambit, KomodoDragon won as black) 

Season 23 premier division, final results

Final standings

Stockfish and Leela will play in the superfinal of season 23. Stockfish led from the start and gradually increased the gap to second place. It had no losses in the league, beating KomodoDragon in all 4 game pairs and beating Leela once. Leela and KomodoDragon raced for second place, each had one game pair win in their head to head games. The race was decided in the last round, KomodoDragon's loss to Stockfish meant that the scores were tied and Leela won on a tiebreak - mainly due to a better result against Stockfish. Leela returns to the superfinal, in season 22 it was KomodoDragon that had a better score.

rofChade and Berserk are relegated to league 1. As the division progressed they dropped further behind the other engines and there was little doubt they would not survive. Together they have only one game pair win, where rofChade beat Berserk. rofChade has been moving between league 1 and the premier division for the last several seasons, last season it finished 4th in the premier division - its best result so far. Berserk had hopes of surviving the premier division, based on its results in the last Swiss tournament. Apparently it is not ready for a multi-DRR event with the best TCEC engines.

The top3 engines were much better than the bottom5, winning 51/60 game pairs without loss. This is a recurring phenomenon in the premier division. KomodoDragon drew only one such game pair, compared to 4 each for Stockfish and Leela. This is why its score does not reflect its losses within the top3.

Ethereal finished 4th in the division, this is its best result in TCEC. In season 22 it was not able to advance to the premier division, finishing 5th in league 1. Since then it has improved significantly, though still not at the level of the top3.

The next TCEC event will be a match between KomodoDragon and Ethereal (bronze medal match?). Considering the results of the premier division this will probably be a one-sided event and KomodoDragon should win by a large margin. The superfinal will follow, it should be less one-sided than last season's superfinal but Stockfish is still the favorite to win.

Interesting games

game 170, Ethereal - Stoofvlees: Ethereal created a passer in the center with all the pieces still on the board. After a few exchanges Ethereal connected a second passer, then went a pawn up and evals started to increase. Ethereal placed a protected knight on d6, then used the threat of forking the queen in a combination that started with a rook offering and ended in a winning BN vs pawns ending. 

game 171, Stockfish - Berserk: The game started with a 22-ply book in the KID Saemisch variation, with a Q vs BB imbalance and black two pawns up. Evals increased from the start, Stockfish captured two pawns and created a central passer. Berserk regained some material and the engines reduced to a QN vs RBN position. After a few pawn trades and some shuffling Stockfish traded pieces and the game reached a N vs B ending. Material was not equal for long, Stockfish went two pawns up and created 3 passers. Berserk also had a passer but Stockfish queened first, the game ended in a tablease win.

game 178, Stockfish - rofChade: Stockfish captured a bishop for two pawns very early, the white king was exposed and protected by pieces. rofChade had its queen and a pawn very close to the white king but Stockfish kept its king safe and evals increased. rofChade gave material and the game reached a QRB vs QB position, black 3 pawns up and still chasing the white king. rofChade captured another pawn, it took Stockfish 30 moves to get its king out of the way and exchange queens. The black pawns fell one by one and the game ended in a tablebase win.

game 179, Leela - Stoofvlees: Leela's eval increased quickly after the start, it gave a bishop for 3 pawns and exposed the black king. Stoofvlees lost a knight while defending its king, the engines reduced to a RN vs RB position with white two pawns up. Stoofvlees captured no less than 4 white pawns, creating 3 connected pawns on the queen side. However, Leela created a central passer and Stoofvlees gave the rook to stop it, followed by mate.

game 180, KomodoDragon - Berserk: Berserk captured a pawn on the king side, KomodoDragon castled long and its eval jumped. The white rooks moved to the king side, Berserk tried to get its king away but couldn't. KomodoDragon opened the h file and gave a rook for a bishop, then used a mate threat to capture a rook. The engines exchanged queens and the game reached a RBN vs RN position with black two pawns up. Berserk had passers on the king side, after a while KomodoDragon managed to capture a pawn on the queen side and create a passer. The black king was pushed to the corner, the engines continued to trade pawns until only the white passer remained. Berserk could not stop the advancing passer, the game ended in a tablebase win. 

game 182, Stoofvlees - KomodoDragon: Stoofvlees had an advantage in a Q vs RBN imbalance, 3 pawns up with two passers. It chose to exchange a pair of rooks and lost one passer, evals started to go down. Stoofvlees lost a bishop for the second passer and held a draw in a Q vs RN ending.

game 185, Stockfish - SlowChess: The center was locked, the engines exchanged pieces and evals were stable for a while. Stockfish's eval jumped after SlowChess opened the king side, the game reached a RB vs RB position. Stockfish shifted to the queen side, it gave two pawns and created a central passer. After regaining a pawn Stockfish pinned the black bishop on the back rank, by the time SlowChess freed its bishop Stockfish connected a second passer. SlowChess traded bishops but couldn't prevent a queening, game over.

game 187, KomodoDragon - rofChade: There were no pawn exchanges after the start and only one minor piece exchange. Evals were stable until move 37, a pawn exchange opened the a file and KomodoDragon went a pawn up. The engines shuffled for a while, after move 70 evals started to increase as KomodoDragon prepared an attack on the king side. After move 82 a series of exchanges opened the king side, rofChade gave a rook for a knight and the engines reduced to a RB vs BN position. The engines traded pawns, both had passers that seemed equally dangerous. However, both engines agreed that KomodoDragon was winning, the game ended in a tablebase win that included both engines queening and a queen ending with white a pawn up. 

game 196, Stoofvlees - rofChade: There were no exchanges until move 19, then the engines exchanged a pair of pawns and opened a file on the queen side. They later exchanged a pair of rooks through the open file. There was a long period of mostly shuffling, including a few pawn moves and a bishop exchange, evals slowly increased. Stoofvlees pushed pawns on the king side and on move 70 the king side finally opened. rofChade gave a knight for two pawns to keep its king safe, then it gave a rook for a bishop. After exchanging queens only RN vs N remained, Stoofvlees created an unstoppable passer to win.

Standings after RR7: Stockfish +18, Leela KomodoDragon +13, Ethereal 0, Stoofvlees -7, SlowChess -9, rofChade Berserk -14. Leela failed to win as white against Ethereal and SlowChess, within the top3 all games were drawn. KomodoDragon has a good chance of finishing second. Berserk and rofChade will surely be relegated.

game 201, KomodoDragon - SlowChess: The engines castled in opposite directions, evals increased from the start. The engines exchanged minor pieces and opened a file in the center, KomodoDragon moved its queen to the king side and pinned a bishop that protected the black king. SlowChess gave a pawn and opened the queen side, KomodoDragon blocked the files and moved more pieces to the king side. KomodoDragon captured another pawn and then reduced to a N vs R position. It used an unstoppable passer to win.

game 202, Leela - Berserk: The engines played out a long PV agreement where the queens were exchanged and Leela captured a rook for a knight and pawn. Evals slowly increased as the engines arranged their pawns, then Leela's eval jumped when in a series of exchanges the game reached a RN vs R ending. Berserk was two pawns up with a central passer, Leela captured the passer and created one of its own that Berserk couldn't stop. the game ended in a tablebase win.

game 203, Stockfish - Stoofvlees: The center was locked, Stockfish castled long and Stoofvlees pushed pawns on the queen side. Stockfish pushed pawns on the king side, Stoofvlees castled short and Stockfish thought this was the wrong time to do it. Stockfish's eval jumped as it sacrificed a bishop for a pawn, then a rook for a bishop and opened the king side. Stoofvlees tried to counter on the queen side but was not strong enough. Stoofvlees gave material to protect its king, its queen and rook were too far to help. Stockfish mated with queen and knight. 

game 204, Ethereal - rofChade: There was one pawn pair exchanged after the start, evals were stable until move 24 when Ethereal's eval jumped though the advantage was not apparent. The engines exchanged a few pawns and pieces including queens, then mostly shuffled while evals increased slowly. On move 58 Ethereal went a pawn up, rofChade pushed a pawn that became a passer. The game reached a RB vs RN position and Ethereal captured the black passer. Ethereal played patiently, it slowly captured black pawns until by move 100 all the black pawns were gone and it was 4 pawns up. The game reached a tablebase win not long after.

game 210, KomodoDragon - Stoofvlees: Stoofvlees captured an early pawn, but it moved its king without castling. There were many early exchanges and the game reached a QR vs QR position on move 19. Evals jumped on move 22, KomodoDragon regained the pawn and threatened the exposed black king. Before long the black king had to run with the white pieces chasing, KomodoDragon won material and finally mated.

game 211, Leela - rofChade: The engines castled in opposite directions, Leela pushed pawns on the king side. There were many early exchanges and the game reached a RB vs RN position on move 24. Leela went a pawn up, rofChade created a passer on the king side while Leela had a 3 vs 1 pawn majority on the queen side. Leela won the pawn race and queened first, the game ended in a tablebase win.

game 212, Stockfish - Ethereal: There were no exchanges until move 19. A few pawn exchanges opened the queen side and evals started to increase. Ethereal went a a pawn up with a passer on the queen side, after exchanging queens Stockfish regained the pawn and the game reached a RBB vs RNN position. The white king moved forward and the white bishops covered many squares in the open board. Ethereal moved its king to support the passer, this opened the way for the white king to attack the king side. Stockfish created an unstoppable passer, Ethereal gave a rook for a bishop to capture it. Stockfish created another passer, both engines queened but Ethereal lost material and was mated.

Three rounds to go, Leela and KomodoDragon have the same score in joint second place. Leela has a tiebreak advantage because it only lost to Stockfish once compared to KomodoDragon's 3 losses. Leela's remaining games are white against Stockfish, black against Ethereal and SlowChess. KomodoDragon's remaining games are white against Ethereal, black against Stockfish and rofChade. KomodoDragon has a good chance of reaching the superfinal if it holds against Stockfish, which it has not been able to do so far in this division.

game 216, Stoofvlees - Berserk: Evals were stable after the start while the engines exchanged a few pawns and minor pieces. Berserk went a pawn up and it had connected passers on the queen side, Stoofvlees had a 2 vs 1 pawn majority also on the queen side. Evals started to increase, Stoofvlees captured one of the passers and created a passer of its own. The game reached a RB vs RN position, Stoofvlees used a mate threat to exchange rooks. Berserk had to block the white passer with its knight, Stoofvlees gave its bishop and captured the remaining black pawns. The game ended in a tablebase win.

game 219, KomodoDragon - Ethereal: The engines opened the king side, KomodoDragon castled long and Ethereal kept its king uncastled. Ethereal captured a pawn on the king side, KomodoDragon captured a pawn on the queen side and created a passer. Ethereal captured a pawn in the center but evals started to increase. Ethereal gave a rook for a knight to capture the white passer, after exchanging queens KomodoDragon again had a passer on the queen side. The game reached a RB vs BN position, Ethereal had 3 passers on the king side but it was too busy with blocking the white passer. KomodoDragon captured pawns, it got a bishop for the passer and the game ended in a tablebase win.

Leela only managed a draw against Stockfish. Before the last round KomodoDragon is in second place 0.5 points ahead of Leela.

game 221, SlowChess - Leela: Evals came down from the start, Leela had no problems equalizing and the game seemed to be heading for a draw. There was some excitement when Leela's evals became negative after move 32, close to 0 at first and then jumping a little. Leela threatened to create a passer on the queen side, it doubled rooks in an open file and for a few moves SlowChess' eval was negative as well. However SlowChess managed to hold, most pieces were exchanged and evals came back down.

game 222, Stockfish - KomodoDragon: See featured game below. 

Stockfish beat KomodoDragon for the fourth game pair in a row. As a result Leela moves to second place on a tiebreak. 

game 223, Ethereal - Berserk: Ethereal's eval started to increase after it gave a pawn and opened a file in the center. Ethereal created a passer in the center through an exchange, then it regained the pawn and placed all the major pieces on the open file. Berserk exchanged pieces and the game reached a RN vs RN position. Ethereal went a pawn up though it lost the passer, the white king moved forward to the center of the board. Ethereal managed to capture all the black pawns and was 3 pawns up, the game ended in a tablebase win.

Featured game: Stockfish - KomodoDragon
game 222

After the start the engines lined up their pawns on the queen side. Starting from move 14 the engines played out a long PV agreement, they opened the d file in the center and exchanged queens. Towards the end of the PV agreement evals started to increase though KomodoDragon was a pawn up with a doubled central passer. 

Stockfish moved its knight to a5 and attacked the weak black pawn on c6. KomodoDragon protected the pawn with its bishop, which became trapped in the corner. The game reached a RBN vs RBN position and Stockfish regained the pawn. KomodoDragon tried to keep the files blocked so the white rook couldn't attack. KomodoDragon moved its rook forward and there it became trapped in the center. 

Stockfish had too many threats for KomodoDragon to defend, in the end Stockfish captured the c6 pawn and won the rook for a bishop. The black bishop was released from the trap in the corner. Stockfish moved its rook to the 7th rank and pushed its c pawn forward. KomodoDragon had to give its knight to avoid a queening.  

The game ended a few moved later in a tablebase win. 

Season 23 premier division, after RR6

Standings after RR6

In the third DRR the top3 beat the bottom5 in 12/15 game pairs, Stockfish drew against Ethereal and SlowChess, Leela drew against rofChade. Stockfish beat KomodoDragon for the third time, it is still in the lead extending the gap a little. KomodoDragon beat Leela and is very close to second place. Leela can't afford dropping games against the bottom5 or losses within the top3 if it wants a superfinal spot.

Within the bottom5 almost all game pairs were a draw, only Ethereal and SlowChess managed a game pair win against Berserk and Stoofvlees respectively. rofChade and Berserk are last 1.5 points behind the rest, they will probably be relegated.

Interesting games

game 114, Ethereal - Stoofvlees: The game started with a black bias in a variant of the KGA Schallop defense. There were no exchanges after the start, Stoofvlees moved its king without castling and pushed pawns on the king side. On move 26 there was a series of exchanges and queens were off. Evals remained stable, Ethereal gave a knight for two pawns and the engines reduced to a RB vs RBN position. Ethereal had a passer on the queen side and a rook on the back rank. On move 47 it blundered and evals immediately jumped, Stoofvlees managed to capture a pawn and was on time to give a rook for the passer. In the R vs BN ending Stoofvlees had one last pawn that ensured a win.

game 115, Stockfish - Berserk: After the start Stockfish captured a rook and later lost a knight. Stockfish castled long while Berserk kept its king in the center and evals started to increase. On move 25 Stockfish gave the material back and opened the king side. Queens were exchanged and Stockfish went a pawn up, then in a RBB vs RBB position it captured a second pawn and created a passer. Very slowly Stockfish pushed the passer forward, Berserk started to lose material and was mated.

game 116, Leela - KomodoDragon: See featured game below. 

game 119, Stoofvlees - Stockfish: The game started with a black bias in a line of the English Symmetrical opening where black is up a rook and two pawns for a knight. Stockfish had connected passers on the queen side. Stoofvlees forced the black king to move to the king side without castling, Stockfish gave a rook to capture a forward knight. Stockfish couldn't develop its king side pieces, it even offered to give a rook for the white DS bishop but Stoofvlees refused. On the queen side Stockfish pushed a passer and captured a rook for it. Then Stockfish gave a bishop to develop its king side rook. In a QBN vs QRB position 3 pawns up Stockfish saw mate in its PV, game over.

game 122, Stockfish - rofChade: Stockfish played the opening better and evals started to increase. It pushed pawns on the king side and prepared an attack on the black king. Both kings were exposed but Stockfish was faster, it won material and reduced to a RRN vs RBN position. Progress was slow, it took 20 moves for Stockfish to capture a pawn and create a passer, then 20 moves more to mate.

game 123, Leela - Stoofvlees: The game started with a 2-ply Owen defense book, Leela played the opening better and evals increased. Stoofvlees gave a rook for a knight and pawn, it held on until move 25 when it captured a pawn. Evals immediately jumped and a few moves later Leela captured a knight. Stoofvlees managed to capture a bishop and stay close to equal material, but after exchanging queens the R vs B ending was a win for white.

game 124, KomodoDragon - Berserk: The engines castled in opposite directions, evals started to increase even though Berserk was a pawn up. The engines opened the f file and KomodoDragon attacked the black king. It captured a rook for a bishop while the black king hid behind a white pawn. The game reached a QRR vs QRB position, KomodoDragon had connected passers on the king side. After exchanging a pair of rooks Berserk captured a passer and lost its rook, KomodoDragon mated a few moves later.

game 129, Stockfish - SlowChess: The game reached a rook ending with Stockfish a pawn up on move 46. For 4 moves Stockfish's eval increased as it created a passer on the queen side. Its eval was close to 6 on move 50, then on move 51 Stockfish's eval dropped to 0 and the game was adjudicated a draw a few moves later. This is very unusual for Stockfish, there was plenty of time to think, what happened here?

game 130, Leela - Ethereal: Leela castled long and Ethereal kept its king in the center. Evals drifted down and it seemed the game was heading for a draw. On move 28 Ethereal diverged from the PV of both engines and evals jumped, why? Ethereal went a pawn up, Leela threatened the black king through an open h file. After many moves of back and forth between the king and queen side Leela managed to capture a pawn on the queen side on move 63 and it created connected passers. The engines exchanged queens, then Leela trapped and captured a bishop for a pawn. In a RBN vs RN position Ethereal couldn't prevent a queening and mate.

game 131, KomodoDragon - rofChade: The engines castled in opposite directions, evals were mostly stable as the engines exchanged pieces and the game reached a RRB vs RRB position. KomodoDragon had a passer on the queen side and evals started to increase. Using a pawn exchange KomodoDragon added a second passer, and it pushed them slowly with the support of its pieces. KomodoDragon gave a rook for a bishop, then captured a rook for a passer. rofChade couldn't stop the second passer, KomodoDragon queened and mated.

game 132, Berserk - Stoofvlees: The engines castled in opposite directions, Berserk pushed pawns on the king side facing the black king. Stoofvlees gave two pawns and opened the queen side, evals started to increase. Berserk captured a third pawn, then gave a rook for a knight and moved its queen to the back rank. Stoofvlees managed to regain 3 pawns, equalize material and reach a QR vs QR position. The white king was totally exposed but it found a safe square, the initiative returned to Berserk that continued to chase the black king and mate.

game 133, SlowChess - Stoofvlees: The game reached a RRB vs RRB position on move 28, with almost all pawns on the board. SlowChess created a passer in the center, Stoofvlees gave a pawn on the king side and hid its king behind a white pawn. Stoofvlees created passers on the king side yet evals started to increase. Both white and black passers reached the 6th rank, after a pawn trade more passers were created and all were racing forward. In the end all passers were caught, Stoofvlees lost a bishop in the process. The black king was trapped on the h file, SlowChess mated with its rooks. 

game 135, Ethereal - KomodoDragon: The game started with a black a pawn up in the Slav defense, Geller gambit. There were many exchanges after the start, the game reached a RN vs RN position on move 31 with black a pawn up. Ethereal had a passer on the queen side, KomodoDragon captured a second pawn and created 3 passers on the king side. The engines exchanged knights and the game ended in a tablebase win.

game 137, Leela - SlowChess: SlowChess was up a pawn from the start, Leela forced the black king to move without castling. On move 21 Leela surprised SlowChess and evals jumped, Leela quickly opened the queen side and placed its major pieces there while SlowChess still had a trapped rook on the other side. SlowChess lost material, it managed to free its rook but was mated anyway.

game 140, Stoofvlees - rofChade: There were a few exchanges after the start, the a file was open but there were long pawn lines across the rest of the board. Evals went up and down, the engines mostly shuffled for long periods and the likely outcome was a draw. On move 84 evals jumped unexpectedly, Stoofvlees pushed a pawn and opened the position in a series of exchanges. The game reached a RBN vs RBN position, rofChade traded a trapped bishop for two pawns and the engines reduced to a RB vs R ending. Stoofvlees captured all the black pawns, the game ended in a tablebase win.

Standings after RR5: Stockfish +14, Leela +11, KomodoDragon +10, Ethereal -3, Stoofvlees -4, SlowChess -7, Berserk -9, rofChade -12. KomodoDragon beat Leela, it is still fighting for a place in the superfinal. Stockfish only managed a draw against SlowChess, only top3-bottom5 game with a hold against the bias.

game 142, Stoofvlees - Ethereal: The game quickly diverged from the reverse game 114. Stoofvlees had strong pawns in the center, Ethereal's (negative) eval increased fast though it was two pawns down and its king uncastled in the center. Stoofvlees thought its was fine, it gave two minors and opened the center, then captured a rook. Stoofvlees realized it was in trouble but it was too late. Ethereal captured a rook for a knight, the black king was exposed to attack but Ethereal managed to keep it safe despite the white queen and rook on the 7th rank. Ethereal exchanged pieces until only RN vs RBN remained, then gave a rook for a knight and queened a passer in the center. The game ended in mate. There were two black wins in this game pair.

game 145, KomodoDragon - SlowChess: Evals started to increase though the engines' PVs mostly agreed.  The engines exchanged pieces until only QRN vs QRN remained on move 26. The engines exchanged queens and KomodoDragon moved its rook to the 7th rank. KomodoDragon went a pawn up, it had 3 connected passers on the king side and SlowChess had 2 passers on the queen side. KomodoDragon pushed the passers forward, it captured a rook for a knight and the game ended in a tablebase win. 

game 146, Leela - Berserk: Pawns were locked in the center and king side, Leela moved its queen forward on the queen side. Evals increased as the engines exchanged queens and Leela created a pawn majority on the queen side. Leela castled late and moved both its rooks to the queen side to support the pawns. Leela then gave a knight for 3 pawns and created connected passers in the center. Berserk gave a bishop for one passer, the game reached a RRB vs RRB position with Leela two pawns up. Leela pushed two passers to the 7th rank, Berserk lost a rook for one and was soon mated.

game 154, KomodoDragon - Stoofvlees: The engines played out a long PV agreement that led to a RBN vs Q imbalance. The black queen moved forward and cleared the white queen side pawns, Stoofvlees was up two pawns. Evals increased after move 28, KomodoDragon played the complicated position better. The engines were down to one pawn each when KomodoDragon started to chase the black king. It traded RB for Q and reduced to a tablebase win.

game 160, Stoofvlees - Berserk: The engines castled in opposite directions, Stoofvlees pushed a pawn to h6. Evals increased slowly as the engines exchanged pieces, the black king walked out of the corner back to the center. In a series of exchanges the engines reduced to a knight ending. Stoofvlees used its king to trap the black knight, Berserk had to protect a pawn on the queen side and to stop any attempt to get behind the pawns on the king side. In a zugzwang Berserk gave the pawn, this freed its knight and it managed to capture two pawns. However, the white knight moved forward and the h6 pawn became a passer. The game ended in a tablebase win.

game 166, Stockfish - KomodoDragon: Evals increased from the start, after all pieces were developed a white bishop controlled the f8 square and KomodoDragon was forced to castle long. However, Stockfish moved its rooks to the queen side and KomodoDragon decided it would be better for its king to walk back to the king side. The black king was exposed, KomodoDragon gave a rook to remove a forward knight. After some shuffling Stockfish opened the queen side and went two pawns up in a QRB vs QBN position. Both engines saw the mate 15 moves in advance.

game 167, Ethereal - Berserk: Ethereal pushed pawns on the king side and Berserk kept its king in the center. Almost all pawns were on the board except for the open c file, evals started to increase in a short period of shuffling. Berserk felt its king was not safe, it walked to the king side while Ethereal opened the king side and went a pawn up. A series of exchanges reduced to a RNN vs RNN position, Ethereal captured a second pawn and pushed a passer on the king side. Eventually Berserk lost a knight for the passer, Berserk tried to hold but Ethereal started to chase the black king with its pieces. Berserk lost more material and the game ended in mate.

game 168, rofChade - Stoofvlees: rofChade castled long and Stoofvlees kept its king in the center. Stoofvlees didn't see move 17 coming, rofChade's eval jumped and it sacrificed a rook in the center. Stoofvlees saw its king was in danger and it did not capture the rook, rofChade put all its major pieces on the open d file. Stoofvlees tried to defend, it traded a pair of rooks but it was hopeless. The black king was soon in the open, rofChade chased it and mated. There were two white wins in this game pair. 

Featured game: Leela - KomodoDragon
game 116

The game started with a black bias in a variant of the Vienna gambit. KomodoDragon went a pawn up but it had an unsupported forward pawn on c3. The engines developed pieces and castled in opposite directions, Leela captured the black pawn on c3 and equalized material. KomodoDragon's (negative) eval started to increase, the engines exchanged pieces until only RRB vs RRN remained. 

The engines exchanged a pair of rooks and Leela's (negative) eval jumped. Leela pushed the d pawn and created connected passers in the center, this gave KomodoDragon a 3 vs 1 pawn majority on the queen side. Leela captured a pawn on the queen side and gave a rook for a knight to capture another. 

KomodoDragon let the a pawn be captured but got rid of the white central passers. Leela protected its a pawn with the bishop, KomodoDragon used its rook to push the white king to the corner. Leela needed the bishop to control g6 and keep its king side pawns safe.

KomodoDragon chased the white bishop away, Leela tried to protect its passer and couldn't avoid KomodoDragon capturing the two pawns on the king side to win.

Season 23 premier division, after RR4

Standings after RR4

In the second DRR the top3 engines beat the bottom5 by 14/15 game pairs, only SlowChess scored a draw against Stockfish. Both Stockfish and Leela beat KomodoDragon, they lead the table at the halfway point. KomodoDragon needs wins within the top3 if it wants to have a chance of getting to the superfinal this season. 

Within the bottom5 engines Ethereal and Stoofvlees have 3 game pair wins, with Ethereal beating Stoofvlees the only loss. Berserk and rofChade are last with two game pair losses each, they are the most likely candidates for relegation, though SlowChess is not too far ahead.

Interesting games

game 58, Ethereal - Stoofvlees: Ethereal was a pawn up, Stoofvlees pushed pawns on the queen side and created a passer. This also gave Ethereal a strong center with a pawn majority, evals started to increase. The black pieces surrounded the black king with a backward pawn on e7. Stoofvlees untangled itself by giving a bishop for the two central pawns, the engines reduced to a RB vs R position. Ethereal captured black pawns until Stoofvlees gave its rook in desperation, game over.

game 59, Stockfish - Berserk: The game started in the Dutch defense Leningrad variation, in a line played at the highest levels of human chess. Berserk deviated from known theory quickly, Stockfish pushed a pawn to c6 and Berserk tried to blockade with a pawn line. Berserk went a pawn up and opened the king side, then gave a rook for a bishop, it seemed to be holding for a long time. Stockfish's eval came down even after it gave a pawn and the c pawn became a passer on the 7th rank. On move 53 Berserk apparently blundered, Stockfish had less than 40 seconds on the clock when its eval jumped. Berserk expected the next move but regretted its move immediately. The engines reduced to a RR vs RN position, the white rooks dominated the board. Berserk captured the passer but it slowly lost material and the game ended in a tablebase win.

game 60, Leela - KomodoDragon: See featured game below. 

game 65, Ethereal - SlowChess: After pieces were developed the white queen moved forward to capture a pawn. A series of exchanges followed and only QR vs QR remained on move 34. The black king was more exposed, Ethereal managed to capture a second pawn and then reduce to a tablebase win.

game 66, Stockfish - rofChade: Stockfish was a pawn up from the start, evals started to increase after a few moves. rofChade gave a second pawn, I'm not sure why but it didn't expect Stockfish to capture it. Stockfish gradually exchanged pieces until only RN vs RB remained. rofChade got a pawn back, after some preparations Stockfish traded pawns and created connected passers in the center. rofChade gave a bishop for the passers, Stockfish captured all the black pawns and reduced to a tablebase win. 

game 67, Leela - Stoofvlees: There were many exchanges after the start, Leela went a pawn up but evals appeared to be drifting down. The game reached a RB vs RB position, on move 37 Leela's eval jumped. Stoofvlees thought it was ok for another 7 moves before it realized the advancing white pawns were dangerous. Leela pushed a passer to the 7th rank, Stoofvlees decided not to give a rook to stop it. Leela under-promoted to a rook, still strong enough to mate a few moves later.

game 68, KomodoDragon - Berserk: The engines traded R and two pawns for BN after the start, the black king walked to the king side and the white king castled long. Berserk tried to develop its king side rook through the h file, it offered a rook trade that KomodoDragon thought was a mistake. KomodoDragon reduced to a B vs pawns endgame, it captured black pawns and created an unstoppable passer to win.

game 69, SlowChess - Berserk: There were very few exchanges from the start, SlowChess pushed a pawn to a6. After move 30 a series of exchanges opened the king side and evals started to increase. SlowChess had a passer in the center that Berserk blocked, after more piece exchanges SlowChess moved  a rook forward and Berserk couldn't prevent it from creating a second advanced passer. Berserk lost a rook for a passer and mate followed.

game 74, Leela - Ethereal: There was one pawn exchange after the start, opening a file in the center. The engines exchanged pieces gradually, all rooks were exchanged through the open file, evals were stable for nearly 40 moves. On move 39 Ethereal blundered and allowed Leela to reduce to a knight ending, material was equal but Leela had a king side passer. Leela used zugzwang to capture a pawn, and it still had a passer. After a few pawn trades Leela gave the knight and deflected the black knight so it could queen the passer, game over.

game 75, KomodoDragon - rofChade: There were no exchanges and the engines built pawns walls from side to side. The queen side and center were locked, a pawn exchange opened the c file. Evals started to increase after the king side opened, both kings were exposed but KomodoDragon managed to walk its king to the center. KomodoDragon offered a rook for a bishop and rofChade refused to take, not wanting to create an advanced white passer. Instead KomodoDragon captured a rook for a bishop, then captured two pawns and reduced to a winning R vs B ending.

game 79, Ethereal - KomodoDragon: The game started with an 18-ply book in the French Steinitz Boleslavsky variation, played in human chess. KomodoDragon chose a line where it sacrifices a knight for two pawns and opens the queen side, still in theory. Evals increased steadily, KomodoDragon pushed pawns on the queen side and Ethereal blocked them with pieces. The engines opened a file on the king side and exchanged all rooks, only BNN vs BN remained. Evals were over 5 when Ethereal gave a pawn on the king side, KomodoDragon's eval dropped as it gave a knight for a pawn on the queen side. Despite having two extra pieces Ethereal needed two knights and a king to block 3 connected passers on the queen side, its bishop wasn't strong enough on its own. The engines shuffled until Ethereal realized it couldn't win.

game 81, Leela - SlowChess: Leela pushed pawns on the king side, SlowChess decided to castle long and evals started to increase. The black queen was out on the queen side and had problems getting back, Leela slowly increased the pressure on the queen side. SlowChess gave a pawn and a bishop, then continued to lose material until Leela mated.

game 84, Stoofvlees - rofChade: The white king moved without castling, there was only on pawn pair exchanged after the start. Stoofvlees pushed pawns on the king side and developed its rook through the h file, rofChade captured a pawn yet evals slowly increased. rofChade chose a sequence of moves that resulted in a QBB vs QR position on move 42. After exchanging queens there was a long period where Stoofvlees' eval did not change, there were only pawns in the center and Stoofvlees took time to plan. On move 90 Stoofvlees was ready and it pushed a pawn, the white king moved forward and on move 109 Stoofvlees captured a pawn and created a passer. The game ended in a tablebase win shortly after that.

Standings after RR3: Stockfish +8, Leela +7, KomodoDragon +4, Ethereal +1, Stoofvlees -2, SlowChess -5, Berserk -6, rofChade -7. Leela had a strong RR with a +4 score including a win against KomodoDragon. Stockfish only drew as white against SlowChess, its lead is only 0.5 points. KomodoDragon's loss puts it behind in 3rd place, it still has to face Stockfish as black in RR4. 

game 89, KomodoDragon - SlowChess: Evals started to increase a few moves after the start, a series of exchanges from move 20 resulted in a QB vs QB position on move 31. SlowChess was a pawn up but its king was in danger. The black king tried to hide behind a white pawn, SlowChess pushed a passer forward and the engines traded passers. The white king came forward, KomodoDragon went a pawn up and created passers on the queen side. After exchanging queens the passers became unstoppable, game over.

game 90, Leela - Berserk: Evals increased after the start, almost all pieces were on the queen side. After several exchanges Leela captured a rook for a knight and pawn. The game reached a RRN vs RBN position, both engines created passers which were then captured. Leela doubled rooks on the 6th rank and Berserk could not avoid losing material. The game ended in a tablebase win.

game 91, Stockfish - Stoofvlees: Stoofvlees castled short despite two white pawns advancing on the king side, evals increased quickly. Stockfish opened the king side and exposed the black king, after a series of exchanges the game reached a QB vs QB position with white a pawn up. The endgame was very slow, Stockfish's eval increased all the time but there seemed to be no progress with repeating moves. After 35 moves Stockfish managed to trade a pair of pawns, then it exchanged the bishops. Next Stockfish gave a pawn and created a passer, the game ended in a tablebase win not long after that.

game 92, Ethereal - rofChade: Ethereal opened the king side and created a passer, both engines castled long. All pieces were on the board until move 30, evals started to increase. There were several exchanges, Ethereal lost its passer and the game reached a QRR vs QRN position with black two pawns up. rofChade had two passers, Ethereal captured one quickly, after some shuffling and exchanging queens Ethereal captured the second passer. As always Ethereal took its time in a winning endgame, the game reached a tablebase win on move 104.

game 93, SlowChess - Ethereal: SlowChess pushed pawns on the king side, the white king moved forward without castling. SlowChess doubled rooks on the half open g file, Ethereal had a bishop that guarded g7. Ethereal tried to attack on the queen side, it gave a rook for a bishop but the pressure continued. The game reached a RRN vs RBB position, SlowChess created connected passers in the center. Ethereal couldn't stop a queening, game over. There were two white wins in this game pair. 

game 97, Berserk - SlowChess: Evals slowly increased, Berserk had a better pawn structure and both the black bishops were passive surrounding the black king. After some shuffling the engines exchanged a pair of rooks and only QRB vs QRB remained. The black king was exposed, using threats Berserk captured pawns until there were none left, mate was unavoidable.

game 98, KomodoDragon - Stoofvlees: On move 14 evals jumped, Stoofvlees didn't notice it trapped its own bishop ahead of its pawns. In a series of exchanges Stoofvlees saved the bishop and even went a pawn up, but now KomodoDragon forced the black king to move without castling. KomodoDragon attacked and soon the black king was in a mating net.

game 99, Leela - rofChade: The engines castled in opposite directions and evals started to increase. Leela went a pawn up and a series of exchanges left a QRR vs QRR position. rofChade had a passer in the center, it tried to protect it but eventually Leela captured it. After exchanging queens Leela pushed connected passers on the king side, rofChade lost a rook and the game ended in a tablebase win. 

game 100, Stockfish - Ethereal: After the start both engines played behind the pawn lines, both engines castled long. Only a few pawns were exchanged and the c file was open. All pieces were on the board until move 30, after the board cleared a little Stockfish doubled rook and queen on the c file and evals started to increase. Stockfish captured a pawn and then reduced to a N vs B ending. It took Stockfish more than 30 moves to convert the win.

game 104, Stoofvlees - Berserk: Stoofvlees pushed pawns on the queen side, Berserk castled short and Stoofvlees moved its king forward without castling. Stoofvlees attacked through the queen side, it traded BN for R and a pawn and created an advanced passer. Berserk gave a rook for two pawns to capture the passer, the white king was exposed to attacks by the black queen. Stoofvlees gave a rook for a bishop and forced a queen exchange, reducing to a winning R vs N ending two pawns up.

game 105, Stoofvlees - SlowChess: The center was blocked, both engines did not castle their kings. Stoofvlees walked with its king to the king side, developing a rook through the h file. SlowChess opened the b file and kept its king in the center. After move 22 evals started to increase, Stoofvlees gave a pawn on the king side and used a black pawn as a shield. After a series of exchanges the engines reduced to a BN vs BN position, Stoofvlees went a pawn up and it had two advanced passers, while SlowChess had one and less advanced. SlowChess lost both its pieces for the passers, the game ended in a tablebase win. 

game 107, KomodoDragon - Ethereal: Ethereal gave a knight for two pawns and pushed pawns on the queen side, following the reverse game 79 for 13 plys after book. Evals increased steadily, KomodoDragon blocked the black queen side pawns, and unlike the reverse game the major pieces stayed on the board. Ethereal gave a rook for a knight and captured white pawns until none were left. KomodoDragon placed both rooks on the back rank, Ethereal delayed with checks but after exchanging queens it was a rook down for two pawns. The game ended in a tablebase win.

game 110, Stockfish - KomodoDragon: Evals started to increase after move 13, Stockfish moved a rook forward with a tempo by attacking the black queen. After exchanging queens PVs mostly agreed, the engines exchanged pieces until only RN vs RB remained with white two pawns up. Stockfish had two passers but it was patient, after 30 moves KomodoDragon gave the bishop to capture one passer. The game ended in mate 15 moves later.

game 111, Ethereal - Berserk: Ethereal pushed pawns on the king side and was close to trapping a black bishop, its eval increased from the start. The center opened and both kings walked away without castling. After exchanging queens Berserk was two pawns up but the white rooks were much more active in the open files. The engines exchanged pieces and the game reached a RB vs RN position. Ethereal got a pawn back and created connected passers on the king side, Berserk captured the passers but lost its knight. Ethereal captured all the remaining black pawns, the game continued for almost 50 moves before ending in a tablebase win.

Featured game: Leela - KomodoDragon
game 60

The game started with a 4-ply book in the Dutch defense 1. d4 f5 2.g3 g6. The engines quickly left known theory, Leela pushed a pawn to h6 and despite this KomodoDragon castled short. Leela opened the center, went a pawn up and castled long. KomodoDragon sacrificed a knight, it felt confident it had a strong attack on the white king. 

Leela thought this was a mistake and its eval jumped immediately. The game followed KomodoDragon's PV exactly but its eval jumped as if it was surprised. The attack on the white king was not effective though KomodoDragon gained back material. Leela threatened the black king on the long diagonal, KomodoDragon exchanged pieces and the game reached a BBN vs RB position. 

KomodoDragon had connected passers on the queen side but Leela's bishops stopped their advance. KomodoDragon in desperation gave both its pieces for two pawns and created connected passers on the king side as well. 

Leela was able to queen a pawn first, KomodoDragon deflected the white bishop and pushed the h pawn but it was stopped on the 2nd rank. The game ended in a tablebase win

Season 23 premier division, after RR2

Standings after RR2

As in the previous season, the top 3 engines are a lot better than the rest of the field. In the first DRR the top3 won 12/15 game pairs against the rest, without loss. Stockfish, Leela and KomodoDragon has each "dropped" one game pair with a draw result. Stockfish is in the lead since it also beat both Leela and KomodoDragon in their game pairs. 

Within the botttom5 engines Ethereal and Stoofvlees are a little better with 2 game pair wins. rofChade lost 3 game pairs, it would have been last if not for drawing twice against the top3. This seems somewhat lucky, there is a good chance it will drop down in the coming rounds.

Interesting games

game 1, rofChade - SlowChess: The game started with a 23-ply book in the Sicilian opening, accelerated Dragon variation, with the engines castled in opposite directions. SlowChess pushed pawns and attacked on the queen side, rofChade controlled the center and pushed a pawn to h6. Evals gradually increased as the engines reduced to a double rook ending. rofChade captured a pawn and created a passer on the queen side. The black king walked to the center, rofChade used the time to open the king side and push a rook forward. SlowChess avoided mate and captured the passer on the queen side, but lost a rook for a passer on the king side, game over.  

game 3, Stockfish - Berserk: The game started with a sideline of the Sicilian Dragon, Yugoslav attack. Again the engines castled in opposite directions, Berserk pushed pawns on the queen side. The game quickly reached a QRR vs QRR position and Stockfish pushed a pawn to h6. For a long while it seemed the engines were shuffling but evals slowly increased, on move 44 Stockfish gave a pawn and opened the king side. The black king was threatened, Berserk couldn't hold all its pawns and Stockfish went a pawn up, then reduced to a double rook ending. The white king was safer and Stockfish had connected passers on the queen side, it pushed the passers and captured two more pawns. Berserk couldn't avoid a queening and mate.

game 4, Leela - KomodoDragon: The game started with another variant of the Sicilian Dragon, Yugoslav attack. The engines castled in opposite directions as before, this time Leela captured an early pawn and there were no black pawns on the queen side by move 20. The queens were exchanged, KomodoDragon regained the pawn and slowly pushed pawns in the center while Leela pushed pawns on the queen side with the white king supporting from behind. A black bishop was trapped on the king side and KomodoDragon gave its central pawns to release the bishop. The combination of passers advancing and threats on the black king gave Leela the win.

game 11, Leela - Stoofvlees: Evals did not change a lot in the first 35 moves, the engines exchanged pieces and pawns and opened the queen side. Leela thought move 35 by Stoofvlees was a mistake, Stoofvlees had the game continuation in its PV and thought it was ok. In a QRN vs QRN position Leela moved its rook forward. Stoofvlees tried to counter with a back rank attack but it realized it was in trouble. The white king found safety and Leela started to chase the black king while capturing pawns. Both engines queened a pawn but Stoofvlees couldn't escape and was mated.

game 12, KomodoDragon - Berserk: The game started with a 32-ply book in the Ruy Lopez, Flohr system, with all pieces on the board and one pair of pawns exchanged. There were no exchanges after book and the engines seemed to be mostly shuffling, though evals increased slowly. After move 38 there were a few exchanges, Berserk gave a rook for a knight and tried to push pawns on the queen side. KomodoDragon pushed the h pawn, the engines reduced to a RRN vs RNN position with a pawn on the 7th and 2nd rank. KomodoDragon was a pawn up with a passer in the center, the black king was trapped in the corner. Berserk was forced to lose material, KomodoDragon queened and mated.

game 13, SlowChess - Berserk: Both engines castled long, there was a period of shuffling and then evals started to increase. SlowChess had a bishop pair while Berserk had two knights. The king side opened and SlowChess created a passer in the center, then it captured a pawn and added a second passer on the king side. Berserk captured one passer but lost a rook for the other. After exchanging queens only RBB vs NN remained, the game ended in mate.

game 17, Stockfish - SlowChess: SlowChess was outplayed in the opening though it was a pawn up, evals increased rapidly. The black king could not castle and stayed in the center, SlowChess tried to attack on the queen side but was not effective. Stockfish regained the pawn, then gave a rook for a knight to open the center. Stockfish used the threat to the black king to gain material, mate came quickly.

game 19, KomodoDragon - rofChade: The center was blocked, KomodoDragon had a space advantage and there were only a few black pieces near the black king. rofChade captured a pawn but evals kept increasing, KomodoDragon regained the pawn and opened the king side. The black king was forced to run and KomodoDragon pushed a passer forward. rofChade lost a rook for the passer, it took KomodoDragon another 30 moves to mate.

game 20, Berserk - Stoofvlees: Stoofvlees castled long, Berserk did not castle but moved its king forward. Berserk opened the a file, on move 24 Stoofvlees blundered ignoring its king safety. Berserk doubled rook and queen on the a file and then sacrificed its bishop. Stoofvlees realized too late that its king was in trouble, it tried to move pieces to defend but there were no pawns left on the queen side. Berserk reduced to a Q vs RR position, it pushed a passer to the 7th rank then traded Q for R and added a second passer. Stoofvlees couldn't stop a queening and mate. 

game 24, Stockfish - Leela: See featured game below. 

game 25, Leela - SlowChess: The engines castled in opposite directions, Leela pushed pawns on the king side and doubled rook and queen on the half open f file. Evals increased as Leela placed its knights in the center, SlowChess defended by exchanging pieces, after a long PV agreement only QRR vs QRR remained. Leela captured a pawn and exchanged queens, then slowly pushed a passer on the queen side. After exchanging a pair of rooks Leela captured another pawn, SlowChess had no defense and the game ended in a tablebase win.

game 28, Stoofvlees - rofChade: The engines castled in opposite directions, Stoofvlees gave 2 pawns on the king side and exposed the black king to attack. Stoofvlees doubled pawns on the f file, rofChade gave a rook for a bishop and a series of exchanges reduced to a RBN vs BNN position. After exchanging a pair of knights the engines traded pawns until both were down to their last pawn. The 8-man endgame was very long, the bishops were of opposite color and the black bishop was mostly static defending the pawn. Stoofvlees kept attacking the black knight and king, after 40 moves it managed to trap the black king on the h file. Stoofvlees used the threat of mate to reduce to a tablebase win.

Standings after RR1: Stockfish +3, Leela +2, KomodoDragon +1, Ethereal 0, rofChade Stoofvlees -1, SlowChess Berserk -2. The 3 engines at the top were expected, Stockfish is without loss, it beat Leela and Leela beat KomodoDragon in their first games. Ethereal drew all its games in RR1.

game 29, SlowChess - rofChade: The engines castled in opposite directions, SlowChess pushed pawns on the king side and gave one. rofChade gave a rook for a knight on the queen side and immediately regretted it as both evals jumped over 4. SlowChess gave its queen and attacked the black king, there followed a series of exchanges that left only RRB vs Q on move 28. The white king was protected, SlowChess captured all the black pawns and then slowly pushed the black king back, game over. There were two white wins in this game pair.

game 32, KomodoDragon - Leela: The game repeated the reverse game 4 with a transposition for 27 plys, the engines castled in opposite directions and there were no black pawns on the queen side. Leela saw it was in trouble, it chose not to wait for the advancing pawns on the queen side and it sacrificed two minor pieces for two passers. Leela then attacked the white king and got some of the material back, the game reached a RB vs R position with black two pawns up. KomodoDragon captured one pawn quickly, all remaining pawns were on the king side. Both engines were sure of a white win but it wasn't clear how KomodoDragon could penetrate the black fortress. It took 40 moves for KomodoDragon to capture a pawn, then it queened a pawn and mated quickly. There were two white wins in this game pair. 

game 33, KomodoDragon - SlowChess: There was a diagonal pawn wall in the center, the engines made openings on both sides. KomodoDragon had two advanced knights on the queen side, SlowChess traded a bishop for one and captured a pawn. This allowed KomodoDragon to push a passer to the 7th rank on the queen side. Evals increased rapidly, KomodoDragon moved its pieces forward and the queens were exchanged. KomodoDragon captured two pawns and had a bishop pair advantage, SlowChess lost a rook for the passer and mate followed.

game 34, Leela - Berserk: Leela gave a knight for a pawn, then created an advanced passer on the queen side. Berserk moved its queen forward facing the white king, it thought it was still ok. A few moves later Berserk understood Leela's plan and its eval jumped. With the passer on the 7th rank Leela sacrificed a rook, then pinned and captured the black queen for another rook, and finally trapped a black rook using its king as an attacking piece. The game reached a QB vs RBN position, the white passer was gone and Berserk tried to build a fortress with its pieces. It took Leela another 20 moves to create another passer, then it reduced to a tablebase win.

game 35, Stockfish - Stoofvlees: There was a pawn wall across the whole board except a half open h file, with all pieces on the board. Stockfish had a space advantage, it was unclear how it could penetrate the wall yet evals slowly increased. After a long period of apparent shuffling Stockfish exchanged minors and gave a pawn to open the g file. It took 20 moves to double rooks on the g file with the black king in the corner. Stockfish ended the game with knight and rook sacrifices followed by mate.

game 36, Ethereal - rofChade: The engines opened the c file and Ethereal placed a secure bishop on b6. After a few minor piece exchanges the white king walked to the queen side with evals increasing. rofChade gave a knight for two pawns, creating two passers in the center. Ethereal exchanged pieces and captured the passers, the game reached a RBN vs RN position. It took Ethereal more than 30 moves to capture the remaining black pawns and reduce to a tablebase win. 

game 41, Berserk - SlowChess: Berserk grabbed an early pawn with its queen, the white king stayed in the center without castling and the game reached a RRB vs RRN position. SlowChess gave a pawn, this gave Berserk a passer and a weaker pawn structure. Evals started to increase, SlowChess managed to equalize material but Berserk created a second passer and pushed it forward. SlowChess lost a rook for a passer, Berserk won more material and the game ended in a tablebase win. There were two white wins in this game pair. 

game 42, KomodoDragon - Stoofvlees: KomodoDragon was a pawn up with a bishop pair but its king was stuck in the center with open files on both sides. On move 16 Stoofvlees blundered and gave a knight, it thought it had a strong attack on the white king as compensation. A few moves later Stoofvlees thought long and its eval jumped as well. Stoofvlees got some material back but the white king stayed safe surrounded by pieces. KomodoDragon attacked the black king with its queen, eventually it captured a rook to win.

game 43, Leela - rofChade: Both engines castled long, after exchanging queens evals started to increase slowly. Leela had a bishop pair advantage, the engines reduced to a RBB vs RNN position. rofChade gave a pawn to create a passer, while blocking a white passer on the queen side. While rofChade pushed its passer Leela pushed a pawn on the king side that also became a passer. rofChade couldn't stop this pawn and was forced to lose a rook, leading to mate 15 moves later.

game 44, Stockfish - Ethereal: Evals started to increase after move 20. Stockfish went a pawn up and reduced to a QRN vs QRN position. Most pawns were on the board, the engines mostly shuffled for a while and then Stockfish captured another pawn and exchanged queens. The game reached a rook ending, Ethereal couldn't stop all the advancing white pawns and the game ended in a tablebase win.

game 47, rofChade - KomodoDragon: KomodoDragon chose a line that started with a queen exchange and capturing a pawn, and ended in a RB vs R position on move 25. KomodoDragon was 3 pawns up with 3 passers on the queen side, it tried to protect them and push them safely forward. However, after 20 moves rofChade captured a pawn on the king side and the white rook moved behind the passers. KomodoDragon lost all its pawns and rofChade reduced to a tablebase win. There were two white wins in this game pair.

game 48, Stoofvlees - Berserk: Berserk castled long, Stoofvlees moved its king forward instead of castling, similar to the reverse game 20. Berserk captured a pawn and left two half open files on the queen side with rooks facing the black king. Stoofvlees increased the pressure on the queen side, Berserk started a series of exchanges in PV agreement that resulted in a RRB vs RBN position. Berserk was 3 pawns up and Stoofvlees had a passer on the 7th rank. Berserk captured the passer and exchanged a pair of rooks, but Stoofvlees slowly captured black pawns until it was 2 pawns up. The game ended in a tablebase win. There were two white wins in this game pair.

game 49, Stoofvlees - SlowChess: There were only a few exchanges after the start, the engines mostly played behind their pawn lines. Evals slowly increased after the queens were exchanged. After move 45 SlowChess started to push pawns on the queen side, not sure if that was necessary or it just lost its patience. The queen side opened and the game reached a RRB vs RRN position. Stoofvlees had connected passers in the center, SlowChess gave a knight for a pawn perhaps out of desperation but it couldn't avoid a queening, game over.

game 50, Berserk - rofChade: The game started with a 20-ply book in the Queen's Indian, Petrosian variation, with rofChade a pawn up. The line was played by Karpov in the 1990s. Exchanges opened the center and rofChade castled long. Berserk had active bishops and evals slowly increased. Berserk gave a bishop for two pawns and this left the black king surrounded by pieces without pawn support. Berserk avoided exchanging queens, it used threats on the black king to capture a rook for a bishop. The game reached a RRB vs RBN position, it took Berserk 25 moves to capture all the black pawns and trap the black knight, the game ended in a tablebase win. 

game 51, KomodoDragon - Ethereal: The game started in the Queen's Indian, Fianchetto Nimzowitsch variation, played by Kasparov in the 1990s. KomodoDragon went a pawn up early, there were a few minor piece exchanges in the center. KomodoDragon had a passer in the center but it did not advance, the engines tried to avoid contact and mostly shuffled for a long time. On move 56 there was pawn movement on the king side and KomodoDragon captured a second pawn. Evals started to increase, Ethereal gave a rook for a bishop and tried to attack the white king. In a QRR vs QRB position the exposed white king moved forward to find a safe square, the KomodoDragon reduced to a winning R vs B ending.

game 54, Stockfish - KomodoDragon: Both engines kept their kings in the center without castling, there were many early exchanges and evals increased steadily. Stockfish went a pawn up, the engines reduced to a BN vs BN position on move 31. Stockfish captured the rest of the black pawns by move 48 and the game ended in a tablebase win.

game 55, Ethereal - Berserk: The engines castled in opposite directions, evals increased right from the start. Ethereal pushed pawns on the king side, Berserk kept its king protected and instead Ethereal created a passer in the center. After queens were exchanged Berserk gave a knight for two pawns to capture the passer. The game reached a RRN vs RR position and the endgame as very long. The engines traded pawns and eventually only one white pawn was left. Ethereal was able to keep the last pawn safe, the white king found a square where it wouldn't be in check. Ethereal exchanged a pair of rooks and the game ended in a tablebase win on move 92.

Featured game: Stockfish - Leela 
game 24

The game stared with a 20-ply book in the Queen's Indian, Fianchetto variation. The engines played out a 24-ply PV agreement from the start, evals did not change a lot. On move 23 Leela went a pawn up at the cost of allowing Stockfish to create an advanced passer in the center. Stockfish saw this as a blunder immediately, Leela thought it was perfectly safe.

Stockfish's move 26 surprised Leela, Stockfish gave a bishop but pushed its passer. Leela thought for over 5 minutes and its eval jumped. The passer could not be stopped and Leela lost a rook for it. The exchanges continued and the game reached a RB vs BN position. 

The endgame was very long and slow. Leela tried to keep its pawns for as long as it could, and capture a white pawn when it lost one. By move 58 the engines were down to one pawn each. Leela's eval was only a little over 1 at this point, compared to nearly 15 for Stockfish.

Stockfish prevented the advance of the black pawn, it took 20 moves to get its pawn to the 5th rank. Leela chose to support its pawn with the king, this allowed Stockfish to trap the black king, queen its pawn and mate.