Season 26 superfinal games 71-80

After 80 games Stockfish leads 24-14 with 42 draws. There were five drawn game pairs, 3 with two draws and two with two white wins. Leela hasn't won a game pair in the last 11 pairs. There are only 10 game pairs left in the match, I can safely say that Stockfish will be the champion. 

Games 71-72 started with a 24-ply line in the Four Knights symmetric, Metger unpin variation. All pawns were on the board and the pieces were behind the pawn lines. In game 71 the engines pushed pawns forward and continued to play behind their pawn lines. The first pawn exchange was on move 27, evals increased very slowly. The engines opened the b file, a minor piece exchange opened the c file as well. Leela captured a pawn in the center and the game reached a QRB vs QRN position. 

Leela took some time to arrange its pieces safely, it gave the pawn back and opened a diagonal for its bishop aimed at the black king. Stockfish tried to prevent the white pieces from moving forward, eventually Leela exchanged queens on move 69 and moved its rook to the 7th rank where it captured a pawn.

Leela captured another pawn on the king side, now it had two passers. Stockfish lost more material and the game ended in a tablebase win. 

In game 72 Stockfish blocked the center, Leela pushed pawns on the king side and moved its pieces there. The engines exchanged queens and minor pieces on move 27, all pawns were still on the board. Stockfish's eval started to increase, on move 34 the first pawns were exchanged and the engines opened the a file. 

Stockfish moved a rook forward on the queen side, Leela had to keep a knight on c8 to protect its b and d pawns. The white king moved to the center and Leela captured a pawn on the king side. Stockifsh moved its second rook forward, the black king was under threat and Leela exchanged pawns to try to get more space. Stockfish exchanged pieces and reduced to a RB vs RN position on move 62. It was a pawn down but evals were high. 

Stockfish captured the two black g pawns and created a passer. Leela moved its knight to the king side and Stockfish captured another pawn on the queen side. Stockfish saw the win, the engines reduced to a rook ending, Stockfish queened and mated. There were two white wins in this game pair, Stockfish leads 23-13.

Games 73-74 started with a 21-ply line in the KID orthodox variation, played in high level human games. There was one minor piece exchange and all pawns were on the board. In game 73 Stockfish traded bishop for knight and then gave a rook for a bishop. The center was blocked and it seemed Stockfish wanted to defend behind its pawns. Leela opened the center and gave a pawn, then tried to attack on the king side. Stockfish protected its king and evals came down, the engines reduced to a R vs N position with black two pawns up. The engines shuffled and traded pawns until Leela lowered its eval for the draw rule. In game 74 Leela gave a rook for a bishop, again trying to block the board. Stockfish exchanged a pair of pawns and opened the f file, the engines exchanged bishops and the game reached a QRB vs QNN position. The engines shuffled for a long time, the white king walked to the queen side, then returned to the center. On move 93 Stockfish gave a pawn and shuffling resumed. The game was adjudicated on move 119 after Stockfish gave a rook for a knight.

Games 75-76 started with a 20-ply sideline in the Caro-Kann advance, Van der Wiel attack. All pieces were on the board, there was one exchange of a pair of pawns and both kings were in the center. In game 75 Stockfish forked two minor pieces with a pawn, Leela castled long and pinned the pawn. The black king walked to the king side, Leela captured two pawns but evals came down. Leela captured another pawn and gave a rook, Stockfish was down to its last pawn and its king hid behind the pawn. Stockfish gave the rook back and reduced to a RN vs RNN position. Leela wouldn't lower its eval after exchanging knights, the engines shuffled and the game was adjudicated 25 moves later. In game 76 the engines started to exchange pieces in long PV agreements. By move 23 the game reached a RB vs RB position, the engines continued to trade pawns. Stockfish was a pawn up but evals came down, both engines had a passer on the king side. Not a lot happened, the game was adjudicated when Leela lowered its eval even though Stockfish pushed its passer to the 6th rank. 

Games 77-78 started with a 24-ply line in the Slav, Czech, Carlsbad variation played in high level human games. All pieces were on the board and the d file was open, the black king was in the center. In game 77 Stockfish castled its king, on move 20 the engines started to exchange pieces and the game reached a QRB vs QRN position. Stockfish's eval was 0, the engines exchanged rooks and started to shuffle. After exchanging queens Leela captured a pawn and created doubled passers, but Stockfish controlled them with its knight and prevented the white king from supporting the passers. The game was adjudicated a few moves later. In game 78 the engines exchanged pieces and pawns on the king side, the f file opened and Leela kept its king in the center. Stockfish was a pawn up with a passer in the center, evals came down as the engines shuffled and exchanged a pair or rooks. On move 43 the game reached a QBN vs QBB position, white was a pawn up and its passer was still on the 2nd rank. After exchanging a pair of bishops the game was adjudicated.

Games 79-80 started with a line in the Sicilian Najdorf, Opovcensky variation, played at high level human games but not recently. In game 79 Leela pushed pawns on the king side and Stockfish pushed a pawn on the queen side. As a result Leela went up a pawn and the b and g files were open. The white king walked to the king side and the black king stayed in the center, Leela's eval increased quickly. On move 39 Leela captured a second pawn and created a passer on the king side. 

Very little seemed to change for a long time, Leela pushed its passer to the 5th rank, Stockfish pushed the a pawn. The black king walked to the queen side, starting from move 70 Stockfish's eval started to increase. Leela moved a rook forward and exchanged a pair of rooks. The engines shuffled for a while and Leela's eval jumped, on move 102 Leela captured a third pawn.

After a minor piece exchange nothing could stop the white passer, Leela had two queens and Stockfish had no counter. The game quickly ended in mate. 

In game 80 the engines repeated the first 17 plys, opening the b and g files and Stockfish with a pawn up. Both kings moved forward, evals increased as the engines exchanged pieces. On move 28 the game reached a RBN vs RBB position. 

The pawns stabilized and the engines shuffled for a while, then Stockfish captured a pawn on the queen side, created a passer and exchanged rooks. The black bishops were strong enough to cover the passer's file and Stockfish kept it behind, while its king walked to the king side. When the knight moved to help Leela gave up the h pawn and Stockfish was 3 pawns up with a passer on the king side as well.

Stockfish managed to slowly push the king side passer to the 7th rank with only the black king blocking. Then it slowly pushed the queen side passer forward and Leela gave a bishop to stop it. Stockfish queened the other passer and mated. There were two white wins in this game pair, Stockfish leads 24-14.

Season 26 superfinal games 61-70

After 70 games Stockfish leads 22-12 with 36 draws. Stockfish won two game pairs and extended its lead to +10, the biggest lead so far. There was one game pair with two white wins, Leela was not able to win a game pair. In games 64 and 66 Stockfish won a very long endgame that seemed to be a draw. 

Games 61-62 started with the Zukertort opening, Nimzo-Larsen variation, with an advantage for black. In game 61 the engines blocked the center and exchanged a pair of bishops. Leela pushed pawns on the queen side, (negative) evals came down. The engines opened the queen side, the engines exchanged more pieces and pawns and Stockfish captured a pawn. Both engines used active knights to trade queens and a pair of rooks, leading to a RNN vs RBN position. After clearing the queen side pawns  and exchanging rooks the game was adjudicated. In game 62 the engines exchanged a pair of pawns on the queen side and then exchanged most minor pieces. Leela went up a pawn, Stockfish castled long and (negative) evals came down. After a series of exchanges on the d file the game reached a RN vs RN position. The engines cleared the queen side pawns and then started to shuffle. Leela wouldn't lower its eval for a long time, the game was adjudicated on move 75. 

Games 63-64 started with a 20-ply sideline of the Sicilian, Richter-Rauzer variation. White castled long while the black bishops were undeveloped. In game 63 Stockfish castled long, Leela captured a pawn and opened the f file. Leela moved a rook to the 7th rank, after a while the engines reduced to a RB vs RB position with white a pawn up. The king side was cleared, Leela had a passer in the center. Stockfish stopped the passer on the 6th rank and the engines started to shuffle. Leela wouldn't lower its eval, the game was adjudicated on move 115 approaching a 50-move draw.

In game 64 Leela castled long as well, Stockfish kept the king side closed and exchanged pawns in the center. Stockfish went up a pawn, both engines created passers in the center. Stockfish's eval slowly increased, Leela moved its queen forward and its eval dropped for a few moves. Leela pushed its passer to the 3rd rank, Stockifsh captured a second pawn and created a passer on the king side.

The black queen moved in front of the rook while defending the d3 pawn, Stockfish used this to push its central passer to d7 safely. Combining mate threats and attacks on pieces Stockfish managed to push its h passer slowly forward. Then in a series of exchanges Leela captured both white passers and gave a rook for a bishop. On move 55 the game reached a RR vs RB position.

Leela still had an advanced passer, after exchanging a pair of rooks the passer reached the 2nd rank but the bishop no longer controlled the promotion square. Stockfish saw the win, it created an unstoppable  passer on the queen side. After queening the game ended in a tablebase win. Stockfish wins the game pair, it leads 20-11.

Games 65-66 started with a sideline of the Owen's defense. In game 65 Leela's eval spiked close to 2 early. The engines opened the d file and then Leela thought for 10 minutes and its eval came back down. After a few pawn moves the engines started to shuffle and Stockfish's eval was close to 0. On move 62 the engines started to exchange pieces and pawns, Stockfish gave a bishop for 3 pawns and the game reached a QB vs Q position. After exchanging queens the game was adjudicated.

In game 66 there were many early exchanges and long PV agreements. The black king moved without castling and blocked the king side rook. Once the king walked to h7 the rook was freed, by then Stockfish managed to create an advanced passer on the queen side. The engines exchanged all rooks and the game reached a BN vs BB position on move 36.

Stockfish blocked the black passer and pushed its own to the 7th rank, Leela's DS bishop couldn't attack the passer safely. For a long time the engines shuffled, on move 77 they exchanged a pair of pawns on the king side. Evals stayed low until suddenly Stockfish's eval jumped over 2 on move 86. Nothing seemed to be different, but Leela's eval started to increase slowly as well. The white king moved closer to the passer, slowly Stockfish managed to move its pieces so that it could force a bishop exchange on move 103 (the d8 bishop can escape to e7 but then Bc5+ exchanges anyway).

Stockfish already saw the win. Of the next 19 moves after exchanging bishops the knight moved 15 times, Stockfish captured two pawns and finally managed to queen the passer with the knight blocking the possibility of taking the queen. A few moves later Stockfish mated. Stockfish wins the game pair, it leads 21-11.

Games 67-68 started with a rare line in the Philidor defense, Boden variation. In game 67 the engines castled in opposite directions, Stockfish pushed pawns on the queen side. A black pawn reached a3, Leela blocked the queen side and its eval started to increase. In a long PV agreement Stockfish gave a rook and captured a bishop using a mate threat. Leela gave pawns and opened the king side, after exchanging queens the game reached a RR vs RN position with black two pawns up. 

Stockfish's eval slowly increased, the white rooks were active as defenders and attackers. Leela managed to capture three pawns and created a passer on the queen side. Stockfish had a passer on the king side but it wasn't strong enough. Leela connected a second passer after a pawn exchange, Stockfish could not prevent a queening and mate. 

In game 68 Stockfish castled long, Leela gave a rook for a bishop to open the b file before castling short. Evals stayed below 1 for a long time, in a series of exchanges the engines reduced to a QRR vs QRB position. Leela captured a pawn and all the remaining white pawns were isolated. The engines shuffled for a while and on move 40 they exchanged queens. On move 47 Stockfish started to increase unexpectedly, the engines cleared the king side pawns.

For a long time nothing seemed to happen, Stockfish repeated a lot and Leela mostly waited for Stockfish to do something. Leela's eval didn't change until move 80. Stockfish attacked the black bishop with two rooks, Leela defended with king and rook and was very close to zugzwang. 

The engines blitzed, evals increased quickly and Leela's defense collapsed. The engines traded pawns until there was only one left for each side. Stockfish saw the win in an 8-man position, it offered the pawn but Leela avoided exchanges because a 7-man position was a loss. Eventually Stockfish exchanged rooks and the game was over. There were two white wins in this game pair, Stockfish leads 22-12.

Games 69-70 started with a 20-ply line in the Dutch Stonewall variation, all pieces and pawns were still on the board. In game 69 Stockfish pushed pawns on the king side and exchanged minor pieces. Leela tried to avoid a pawn blockade, the engines exchanged more minor pieces in the center and all knights were gone. Leela opened the b file and evals came down, the engines exchanged a pair of rooks. After some shuffling the engines exchanged queens, the game was adjudicated in a RB vs RB position. In game 70 the engines exchanged a pair of pawns and most minor pieces on the queen side. Evals came down and the king side was blocked. The game reached a QRR vs QRR position and the engines traded pawns. On move 53 the queens were exchanged, evals were low and the game was soon adjudicated.

Season 26 superfinal games 51-60

After 60 games Stockfish leads 19-11 with 30 draws. Leela won a game pair after 14 straight game pairs without a win, losing 6 of them. However Stockfish won 3 game pairs and it extended the lead to 8. One game pair had two black wins. There are only 20 game pairs left to play in the superfinal, it's hard to imagine Leela can close the gap.

Games 51-52 started with a 19-ply line in the Ruy Lopez, Berlin defense, Anderssen variation with an advantage for black. In game 51 there was one pawn exchange after the start, evals were stable and the engines mostly played behind their pawn lines. On move 25 Leela exchanged pawns in the center and Stockfish's (negative) eval jumped over 1. Leela's eval reacted only 6 moves later, the black queen moved forward on the king side and Stockfish prepared an attack on the white king.

Leela couldn't get its king away, Stockfish captured the h pawn and while Leela exchanged pieces Stockfish captured another pawn. The game reached a queen ending with black two pawns up, Leela captured back two pawns but couldn't avoid a queening and mate.

In game 52 Stockfish castled long, it pushed the g pawn forward and opened the king side. The engines exchanged minor pieces and Leela captured a pawn. On move 37 the game reached a QRN vs QRB position with black a pawn up. 

Leela kept its king safe and avoided perpetual check, (negative) evals slowly started to increase. Leela had a pawn majority on the king side, Stockfish captured a pawn on the queen side and Leela exchanged queens. The engines traded pawns and on move 66 Leela had connected passers on the king side and Stockfish had doubled passers on the queen side. 

The black passers were more dangerous and easier to defend. Leela lost the d pawn and captured the two a pawns. It pushed one passer to the 2nd rank, then captured the knight for it. The game ended in a tablebase win. There were two black wins in this game pair, Stockfish leads 16-10.

Games 53-54 started with a 24-ply line in the KID Saemisch variation, with all pieces and pawns on the board except one pair of pawns. In game 53 Leela castled long, it pushed the h pawn and tried to open the king side. Leela's eval spiked over 1.5 for one move and then came back down. In a long PV agreement Stockfish gave both its rooks and a knight and captured the white queen. Despite the material imbalance evals came down quickly, Stockfish captured pawns and was 3 pawns up. The game reached a RRB vs Q position, Leela pushed a passer to the 6th rank and moved a rook forward, but kept its other pieces to protect its exposed king. Evals were low and the game was adjudicated. 

In game 54 after Stockfish castled long Leela pushed the b pawn forward and Stockfish's eval started to increase. Stockfish pushed pawns on the king side, it gave two pawns and opened the g file. Leela saw a few moves ahead in its PV, Stockfish sacrificed a bishop and Leela expected to give back the material. Leela's eval was low while Stockfish's eval was over 3, it surprised Leela with its move 25, a discovered attack on the queen.

Leela thought for 9 minutes and its eval jumped over 3, it lost two minor pieces for a rook. Leela opened the b file and attacked the white king, Stockfish had to be careful. However the white king stayed safe while the black king was under attack. Despite being down on material Stockfish soon saw a win, the engines reduced to a QB vs QB position and the game ended in a tablebase win. Stockfish wins the game pair, it leads 17-10.

Games 55-56 started with a line in the Modern defense, two knights variation, played in high level human games but not recently. In game 55 Leela castled long, its eval went over 1 for a while but after Stockfish castled long Leela's eval slowly came down. A knight exchange opened the e file, Stockfish doubled its rooks there and then closed the file with a bishop. Leela captured a pawn, on move 45 the game reached a RRB vs RRB position. The engines mostly shuffled for a long time, on move 81 Stockfish gave the bishop for three pawns and moved its rooks forward. Leela captured two pawns back but Stockfish had a perpetual check draw. For fun Stockfish chose a different draw, it gave a rook for a white passer and reduced to a tablebase draw a rook down with only two pawns.

In game 56 Stockfish castled long as in the reverse game, however this time Leela castled short. Stockfish opened the g file and Leela's eval jumped over 1.5. In a long PV agreement Stockfish gave a rook for a bishop and two pawns. The engines exchanged queens and reduced to a RBN vs RRN position. Stockfish had connected passers in the center, it exchanged the bishop for a knight and pushed the passers forward.

Leela moved its rooks forward and attacked the white king. Stockfish lost its pieces but queened one of the passers. In the Q vs RR ending Stockfish soon saw the win, the white king found a safe square and Stockfish captured pawns with its queen. Eventually Stockfish queened a second passer and mated. Stockfish wins the game pair, it leads 18-10.

Games 57-58 started with an 18-ply line in the Nimzo-Indian defense that deviated early from standard theory. In game 57 Leela's eval increased from the start, all pawns were on the board and queens were off early. Both kings moved forward without castling, Leela captured a pawn on the queen side and its eval jumped quickly. The pawns stabilized and the engines shuffled, on move 38 Leela's eval was over 8 though it was not clear what the plan was.

The shuffling continued with some pawns moves on the king side, Stockfish's eval increased as well. On move 56 Leela gave a pawn on the queen side and exchanged a pair of rooks, both engines created a passer there. The game reached a RBN vs RBN position, Leela hid its king behind the black passer, on move 62 Stockfish exchanged a pair of pawns on the king side.

Leela pushed the e pawn, it gave the bishop and captured two pawns, creating passers on the queen side. Stockfish lost its rook and then its knight, it pushed its remaining pawns on the king side. Leela gave its pieces to stop the black pawns, then queened to win. 

In game 58 Stockfish castled its king and the queens stayed on the board. The black king moved forward without castling, Leela opened the a file and blocked the center. Evals came down, after some shuffling the engines exchanged a pair of rooks. Stockfish captured a pawn and the game reached a QBN vs QBN position. Leela regained the pawn, after knights were exchanged the game was adjudicated. Leela wins the game pair, Stockfish leads 18-11.

Games 59-60 started with a rare 18-ply line in the French Winawer, advance variation. The center was blocked and all pieces and pawns were on the board. In game 59 the engines exchanged minor pieces and a pair of pawns, the black king stayed in the center uncastled. Evals came down and the black king walked to the queen side. The game reached a QRR vs QRR position and the engines shuffled for a while. Leela captured a pawn, allowing Stockfish to force a queen exchange and the game was adjudicated.

In game 60 Leela pushed a pawn on the queen side, Stockfish gave two pawns and let the black pawn reach the 2nd rank. Evals increased early, Leela's eval was even higher that Stockfish's. Stockfish captured the advanced black pawn and gave a knight, creating a passer on the queen side. Leela's king was in the center and its king side rook could not develop, Stockfish pushed the passer and moved a rook to the 7th rank. Leela lost a bishop for the passer, Stockfish added its queen to the 7th rank. The black king ran to the king side, Leela gave a rook for a knight and pawn. Then Stockfish added its second rook to the 7th rank, all three major pieces on the 7th rank !

Stockfish captured the black a pawn on the 2nd rank, Leela was anxious to get rid of the pieces on the 7th rank and it exchanged queens and a pair of rooks. The game reached a RB vs BN position, Stockfish traded pawns and created a passer on the king side. Leela pushed pawns in the center, Stockfish saw the win in its PV. It lost the passer and captured two pawns in the center, each engine was left with one pawn. Stockfish moved its pieces forward and trapped the black king. Leela lost material because of the mate threat and the game ended in a tablebase win. Stockfish wins the game pair, it leads 19-11.

Season 26 superfinal games 41-50

After 50 games Stockfish leads 15-9 with 26 draws. Stockfish won two game pairs and extended its lead to 6, the highest so far in the match. This is the same result as in the last season's superfinal at the half way point. Last season Leela had a significant comeback in the second half, will we see this again this season? There were two game pairs with two white wins, Stockfish's win in game 46 displayed another case where Leela evaluates completely won endgames as a draw - this time it was an 8-man RB vs RB position with white two pawns up.

Games 41-42 started with a rare line in the QGD, Stonewall variation. In game 41 there were almost no exchanges after the start and all pawns were on the board. Leela pushed pawns on the queen side and Stockfish blocked with its pawns. On move 23 there was on pawn exchange on the king side, Stockfish placed a rook and a queen on the half open h file but Leela protected its pawns there. The engines started to shuffle, the white king walked to the queen side and evals came down. On move 79 Leela gave a pawn, then all rooks were exchanged. The game reached a QB vs QB position and was adjudicated on move 99. 

In game 42 the engines opened the b file and Stockfish moved a rook to the 7th rank. After some shuffling with low evals Stockfish exchanged a pair of rooks and its eval jumped over 1. The engines exchanged queens and the game reached a RBB vs RBN position. Leela's eval was still below 1, it felt safe.

Stockfish's eval went over 2 as it blocked the center, the white king walked to the queen side and the engines shuffled for a long time. Leela's eval also increased though it seemed nothing was happening. Stockfish placed a bishop on b5 and Leela did not capture it on multiple opportunities. The white king moved back to the center, finally on move 91 Stockfish moved the rook to the king side and captured two pawns.

Stockfish gave a rook for the black e pawn, then captured the a pawn, so it had 3 passers. It pushed the a pawn to the 7th rank, Leela managed to capture it with its knight but lost its bishop. Stockfish gave a pawn but secured the h8 square, Leela captured the h pawn and lost its knight. Stockfish queened the 3td passer and mated. Stockfish wins the game pair, it leads 12-7

Games 43-44 started with a 22-ply book in the Sicilian Richter-Rauzer variation. In game 43 the engines exchanged all knights, Stockfish kept its king in the center and its king side rook developed through the h file. The engines played out a long PV agreement and evals started to increase, despite a black doubled passer on the king side. The black king tried to find safety on the king side, Leela captured a pawn on the queen side and created connected passers. Stockfish captured a pawn on the king side and connected another passer there.

Stockfish exchanged a pair of rooks and moved its queen forward, Leela just pushed its pawns forward on the queen side, the c pawn became a third passer. After exchanging queens Stockfish pushed its passers on the king side and Leela stopped them. A series of exchanges reduced to a same color bishop ending, Leela queened twice and mated. 

In game 44 only one pair of knights was exchanged. Evals gradually increased, the engines opened the h file and exchanged a pair of rooks. Leela castled long, then in a series of exchanges the engines reduced to a QBB vs QBN position on move 29.

The black king was exposed and threatened by the white pieces. After exchanging a bishop for a knight Stockfish saw the win, it captured a pawn and waited for the right moment to exchange queens. Stockfish was two pawns up in an opposite color bishop ending, the white king moved forward and Leela couldn't block all the white passers. Stockfish queened and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 13-8.

Games 45-46 started with a rare Queen's pawn, anti Torre line. In game 45 both queens moved forward on the queen side. Leela's eval started to increase early while Stockfish still thought it was safe. In a series of exchanges the queen side was opened, queens were off, Stockfish was a pawn up with a passer on c3. Leela pushed a passer to d6, Stockfish castled long and its eval increased as well. Leela also castled long, the game reached a RRB vs RRN position, Stockfish captured a second pawn while Leela connected a second passer in the center. Stockfish used its two rooks to block the white passers.

Stockfish's only strength was the queen side passers, the black king moved forward and supported their advance. Leela captured the c3 pawn and then cleared the king side and created a passer there. Stockfish managed to switch a blocking rook with a knight and capture the e pawn, but then Leela captured all the three queen side pawns. Stockfish couldn't prevent a queening, the game ended in a tablebase win.

In game 46 the engines opened the queen side and both castled short. Stockfish moved its queen forward and exchanged queens. Evals stayed below 1 though Stockfish captured a pawn, the game reached a RRB vs RRB position on move 39. Stockfish captured a second pawn but both engines were still unconvinced.

The engines traded a pair of pawns and exchanged a pair of rooks, leaving an 8-man position with only two white pawns on the king side. Evals stayed low for a while, perhaps because of the opposite color bishop ending that would be the result of exchanging the rooks. Starting from move 65 Stockfish's eval slowly increased, then jumped over 2 when it pushed a passer safely to h6. Leela's eval became even lower while Stockfish's eval was a clear win, the white king and g pawn slowly moved forward. On move 93 Stockfish's eval was over 90, Leela's eval only 0.32 !!

Leela's eval finally started to react, while Stockfish saw the win in its PV. On move 114 Stockfish pushed the g pawn and reset the 50-move counter, then it drove the black king forward out of the corner. Stockfish queened one of the pawns and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 14-9

Games 47-48 started with a line in the Dutch, Ilyin-Zhenevsky variation played in high level human games. In game 47 the engines exchanged pawns and knights in the center and evals came down. From move 22 the engines exchanged pieces until the game reached a QR vs QR position. Evals were low and the game was adjudicated early on move 37. 

In game 48 the engines exchanged a pair of pawns and a pair of knights in the center, like the start of the reverse game. Then the engines opened the c file and Stockfish moved a rook to the 7th rank. Stockfish's eval slowly increased while Leela's eval remained low. Stockfish moved a second rook forward, in a series of exchanges the queens were off and Stockfish gave a rook for a bishop and two pawns. The black king was exposed and white had two connected passers on the king side, Leela's eval was still low.

Leela thought for 10 minutes and its eval jumped. In a series of exchanges the engines reduced to a rook ending with white a pawn up. Leela also had connected passers but they were slower, and Stockfish had an additional passer on the queen side. Leela tried but couldn't stop the white passers, Stockfish queened twice and mated. Stockfish wins the game pair, it leads 15-9

Games 49-50 started with a the Semi-Benoni variation of the Benoni defense, the center was blocked. In game 49 there were only a few exchanges after the start, Stockfish placed a bishop on h3 and exchanged the other. Leela exchanged a pair of knights and its eval increased to over 1.5. Stockfish's eval came down, it opened the f file and gave a rook for a knight. Stockfish captured a pawn on the king side and the exposed white king walked to the queen side. Leela's eval came down, Stockfish gave another rook for a bishop and threatened the white king. Leela reacted with a threat on the black king through the open g file. The engines reduced to a QR vs QN position and the game was adjudicated. In game 50 the engines exchanged pawns and minor pieces and opened the e file. Evals stayed under 1, after a while the engines exchanged a pair of rooks and evals came down. Stockfish captured a pawn and the game reached a QRN vs QRB position. The game was adjudicated after queens were exchanged.

Season 26 superfinal games 31-40

After 40 games Stockfish leads 11-7 with 22 draws. Stockfish won two game pairs and extended its lead to 4 again. Twice Leela managed to win a game and twice Stockfish won the reverse. In both games 39-40 the losing side saw trouble before the winning side's eval reacted. Were the losing engines seeing ghosts, and proving themselves right with the wrong choice of moves?

Games 31-32 started with an 18-ply line in the Alekhine defense, four pawns attack, played in high level human games. In game 31 Stockfish gave a knight for three pawns in the center. Evals came down as the engines exchanged pieces. The game reached a RB vs R position with low evals and was adjudicated early on move 47.

In game 32 Leela captured a pawn but let Stockfish keep two pawns in the center. Stockfish's eval jumped early, it moved its queen forward on the king side and Leela moved its king without castling. Leela surrounded its king with pieces, it gave a rook for a knight, perhaps hoping that without knights it would be difficult for Stockfish to find a way to attack. However the black king side rook was trapped in the corner.

Evals continued to increase while Stockfish seemed to shuffle. On move 50 the engines exchanged queens, then the game reached a RR vs RN position and the black rook finally moved out of the corner. 

Stockfish cleared the queen side and exchanged a pair of rooks. It saw the win many moves in advance, the white king walked around the board all the way to e7. Stockfish captured pawns and created a passer, the game ended in a tablebase win. Stockfish wins the game pair, it leads 8-5.

Games 33-34 started with a line in the Modern defense played in high level human games, but not recently. In game 33 the engines played out a long PV agreement. At first Leela was up a pawn, but after several piece exchanges Stockfish regained the pawn. The game reached a QRB vs QRB position and evals started to come down. After some shuffling the engines exchanged queens and Leela captured a pawn. Leela couldn't find a way to improve and the engines shuffled, the game was adjudicated as it approached a 50 move draw. 

In game 34 Stockfish gave an early pawn, then regained it and the engines exchanged minor pieces in the center. Evals were stable around 1 until move 20m then Leela gave a rook for a bishop and pawn to expose the white king. There was a long PV agreement, Stockfish exchanged a pair of rooks and was confident its king was safe. Stockfish's eval started to increase very slowly, the game reached a QR vs QN position.

Leela didn't try to chase the white king, its eval drifted down but then started to increase as well. The white pieces without an obvious purpose, then with all pieces concentrated on the king side Stockfish pushed pawns on the queen side. Leela captured the rook for a knight while Stockfish created a doubled passer on the a file. 

Stockfish saw the win, it captured two pawns and created another passer on the king side. Leela blocked and captured one passer but couldn't prevent the queening of the other. The game ended in mate. Stockfish wins the game pair, it leads 9-5.

Games 35-36 started with a 20-ply line in the French Winawer, positional variation. In game 35 Stockfish blocked the center, Leela pushed pawns on the king side and left its king without pawn support. Stockfish opened the b file and created a passer on the queen side, Leela blocked the passer and the white king walked to the center. Regardless of the open file Leela moved its king to the queen side and exchanged a pair of rooks.

Leela opened the king side and exposed the black king. In a series of exchanges Stockfish lost its queen for pieces and the game reached a QB vs QBN position, white two pawns up with a passer on the king side. 

Stockfish captured the passer but Leela captured pawns in the center, Stockfish lost more material and the game ended in a tablebase win. 

In game 36 the engines exchanged pawns in the center, opened the queen side and exchanged queens. The black king moved forward without castling, Stockfish moved a rook forward through the queen side and exchanged a pair of rooks. The game reached a RBB vs RBN position on move 24. Stockfish moved a bishop to f8, the black knight had to stay on e8 to protect the king side pawns.

Leela captured a pawn, evals slowly increased as Stockfish pushed pawns on the king side. After the pawns stabilized Stockfish opened the king side and regained the pawn, Leela exchanged a pair of bishops.

Stockfish captured the black d pawn for its a pawn, the black knight finally moved but Stockfish let it capture a pawn and moved its king forward. The white rook moved forward and Stockfish saw the win. The engines reduced to a rook endgame, Stockfish queened a passer and mated. There were two white wins in this game pair, Stockfish leads 10-6.

Games 37-38 started with a line in the Gruenfeld defense. In game 37 there were no exchanges after the start, both kings walked to the king side without castling. On move 23 a pawn exchange opened the b file, then the engines blocked the center. The engines mostly shuffled for a while and evals came down. From move 39 the engines started to exchange pieces, Stockfish gave two pawns and moved two rooks forward on the queen side. Stockfish traded both rooks, one for a bishop, and then the game reached a QR vs QB position. Leela was a pawn up but Stockfish had enough for a draw and the game was adjudicated. In game 38 Stockfish took over the center and Leela castled its king. The white queen moved forward, in a long PV agreement the engines opened the queen side and exchanged minor pieces. Stockfish castled on move 27, an another long PV agreement the game reached a RRN vs RRB position with white a pawn up. After exchanging a pair of rooks the engines shuffled for a long time, Leela wouldn't lower its eval enough. The game was adjudicated only on move 112.

Games 39-40 started with a line in the Caro-Kann, Steinitz variation, played in high level human games. In game 39 Leela gave a knight for a pawn and forced the black king to move without castling. Evals slowly came down as the black king found safety on the king side, though the king side rook was trapped. Leela had many opportunities to capture the black rook for a knight but decided to keep the knight. In a PV agreement the engines exchanged pieces, suddenly Stockfish's eval jumped, not sure what it saw. The game reached a RR vs RRB position with white two pawns up, Leela's eval remained low.

Leela had a long think and its eval jumped over 2 as well. It captured two more pawns, Stockfish finally developed its trapped rook through the h file. The white king moved forward in the center, Leela had 4 connected passers on the queen side. Stockfish gave the bishop for one passer, the pawn chain was broken but it was not enough. 

Stockfish captured another passer but couldn't stop them all. The game ended in a tablebase win. 

In game 40 Stockfish also gave a knight for a pawn and the black king moved. Leela was surprised by Stockfish's move 12, after thinking for almost 20 minutes its eval jumped over 2. The black king remained in the center, Leela developed its king side rook through the f file and then gave it for a bishop. A knight exchange opened the center, for a while the white queen was stuck on the king side but Stockfish found a way to get it out. It moved all its major pieces to the queen side, then in a series of exchanges the engines reduced to a QB vs QBN position with white 3 pawns up. 

The black minor pieces were static, protecting pawns and themselves. The queens move around the board and Stockfish managed to push the a pawn to a6. It saw the win in its PV, Stockfish exchanged bishops and traded the a pawn for the black c pawn, then captured the black knight for another pawn. This left a queen ending with two pawns up and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 11-7.  

Season 26 superfinal games 21-30

After 30 games Stockfish leads 7-5 with 18 draws. Stockfish won a game pair and extended its lead to +4, but then Leela won two game pairs and the gap is back to +2. There was one game pair with two white wins and one with two draws. Stockfish is in the lead but Leela is fighting back, still a long way to go. 

Games 21-22 started with a rare line in QGD with an advantage for black. In game 21 the engines castled in opposite directions, Leela pushed pawns on the king side and the black queen moved forward on the queen side. After exchanging queens the engines played out a long PV agreement, they opened the center and exchanged most pieces, (negative) evals slowly increased. On move 32 the game reached a RN vs RB position, a few moves later Stockfish captured a pawn and created a passer on the king side. 

Stockfish slowly pushed the passer to the 2nd rank, Leela captured it there but then Stockfish exchanged minors and reduced to a rook ending a pawn up. The black king moved forward, after a while Stockfish captured another pawn and the game ended in a tablebase win. 

In game 22 again the engines castled in opposite directions. Stockfish opened the c and e files, both queens moved forward but they remained on the board. Again there were long PV agreements but evals slowly came down. The engines gradually exchanged pieces and the game reached a QR vs QR position on move 42. The engines shuffled and the game was adjudicated when Leela lowered its eval. Stockfish wins the game pair, it leads 6-2.

Games 23-24 started with a 20-ply line in the Sicilian Scheveningen, Keres attack, that used to be played in high level human games 40 years ago. In game 23 both engines castled long and there were no exchanges after the start. Leela had a space advantage, Stockfish tried to avoid opening the center and traded both its bishops for knights. The h file opened and the engines exchanged a pair of rooks, then a pawn exchange opened the d file on move 47.

The engines shuffled for a long time, Stockfish played waiting moves and Leela tried to find a way into the black fortress. After move 70 evals started to increase, Leela placed a bishop on b6 and restricted the black pieces. Then the white king walked to the king side and Leela slowly arranged its pieces on the queen side. Stockfish moved a rook forward and captured a pawn, but evals were already high. 

In a series of exchanges Leela captured a knight and reduced to a RB vs R position. Leela created a passer on the king side, it was on time to stop the black a pawn and then queened its passer. The game ended in a tablebase win. 

In game 24 the engines again castled long. Stockfish didn't push pawns forward, from move 21 the engines played out a long PV agreement and evals came down. Stockfish gave a rook for two knights, then after exchanging bishops Stockfish captured a rook for a bishop. The game reached a RBN vs RB  position with black two pawns up. Evals were close to 0 despite the material imbalance, Leela created connected passers and Stockfish lost material to stop them and the game was adjudicated. Leela wins the game pair, Stockfish leads 6-3.

Games 25-26 started in the Queen Pawn's game, anti Torre variant, the black queen was out in the center. In game 25 Leela had a bishop pair advantage and queens were exchanged early. Leela had a space advantage, evals increased steadily as it blocked the center and king side. The white king walked to g5 to complete the pawn line on the king side.

Leela attacked the center, Stockfish gave a knight for two pawns and the c file opened. Stockfish moved a rook forward but alone it was weak. Leela moved a rook to the 7th rank and captured the other black rook. Stockfish lost more material and was mated.

In game 26 Stockfish had a bishop pair advantage, but the queens stayed on the board. On move 22 the engines exchanged a pair of pawns and Stockfish created a passer in the center. The engines seemed to shuffle for a while but evals increased steadily. After exchanging a pair of rooks the white queen moved forward on the queen side. Leela still refused to exchange queens, after a series of exchanges the game reached a QB vs QN position with white a pawn up.

Now Stockfish avoided exchanging queens, Leela in desperation gave the knight for two pawns and created passers on the king side, also exposing the white king. Stockfish used the bishop to keep its king safe, then captured pawns and pushed a passer forward. Leela lost its queen and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 7-4.

Games 27-28 started with a short 6-ply line in the French Benoni opening. In game 27 the engines opened the center and exchanged queens. The black king walked to the queen side and the white king castled long. After some more piece exchanges the game reached a RRN vs RRN position, evals were already over 2.

Material was equal but the white rooks controlled the center and restricted the black king. Leela captured a pawn on move 40, then another on move 49 to create a passer on the king side. Stockfish captured a pawn and created a passer on the queen side. On move 57 Leela captured another pawn and was two pawns up.

Leela slowly pushed passers forward and forced Stockfish to exchange pieces. The game ended in a tablebase win. 

In game 28 the engines repeated 19 plys of the reverse game, opening the center and exchanging queens. Stockfish castled long and captured a pawn, then the engines exchanged all rooks through the open center. In a BB vs BN position Stockfish thought it had a small advantage, but its extra pawn was doubled and Leela found a way to block any attempt of attack. The engines shuffled with pawn moves extending the 50-move counter, the game was adjudicated on move 141. Leela wins the game pair, Stockfish leads 7-5.

Games 29-30 started with a 20-ply line in the KID Saemich, closed variation. All pieces were on the board, the center was blocked and the c file was open. In game 29 Leela kept its king uncastled in the center, there were no exchanges until Leela captured a pawn on move 22. Evals came down, the engines exchanged queens and a pair of bishops. The white king walked to the king side and Stockfish opened the f file. In a series of exchanges the engines reduced to a RN vs RN position, evals were low and the game was adjudicated. In game 30 Stockfish captured a pawn and created a passer on the queen side, then it castled its king. The engines exchanged pieces and evals came down, Leela moved a rook forward and the engines shuffled for a while. After exchanging queens Stockfish gave back a pawn and created a passer in the center, Leela gave a bishop and captured the two white passers. The game reached a RN vs R position with black 3 pawns up and was adjudicated.

Season 26 superfinal games 11-20

After 20 games Stockfish leads 5-2 with 13 draws. There were 2 double draws and the first game pair with two white wins. Stockfish won two game pairs and extended its lead. In both cases the win was a long and slow endgame.

Games 11-12 started with a 24-ply line in the French, MacCutcheon, Lasker variation. The white king moved forward without castling and all pawns were on the board. In game 11 the engines blocked the center, Stockfish castled long and Leela captured a pawn on the king side. The pawns stabilized and the engines started to shuffle, with evals coming down gradually. On move 79 Leela moved a pawn to reset the 50-move counter, Stockfish captured the pawn. After a series of exchanges the game reached a QRR vs QRR position, the game ended 20 moves later in a 3-fold repetition. In game 12 Stockfish opened the center and king side, Leela kept its king in the center uncastled. Evals came down and the game reached a QRN vs QRN position. Leela captured the white pawns on the queen side, it had a passer there. Both engines gave checks with their queens, then in a series of exchanges reduced to a rook ending and the game was adjudicated.

Games 13-14 started with the unusual 1. e3 f5 Van't Kruijs opening. In game 13 the engines opened the center in a long PV agreement. The game reached a RBB vs RBN position on move 27 and evals started to come down. The engines reduced to a same color bishop ending, it took another 60 moves before Leela lowered its eval enough for the draw rule. In game 14 there were only a few exchanges after the start. Stockfish pushed pawns on the queen side and opened the b file. Leela pushed pawns on the king side and evals came down. The engines cleared most pawns on the king side and exchanged queens, Stockfish captured a pawn and had a passer in the center. The game reached a RRN vs RRN position with low evals, the game was adjudicated after a pair of rooks was exchanged.

Games 15-16 started with a Pirc, Austrian attack, played in high level human games. In game 15 Leela pushed pawns on the queen side, the engines exchanged a few minor pieces and then started to shuffle. On move 39 the engines exchanged a pair of bishops and continued to shuffle. The white king walked to the center and Stockfish opened the queen side on move 63. The white king became exposed, after the engines avoided exchanges Stockfish moved its queen forward and gave checks. Stockfish gave a rook and cleared the pawns on the queen side. The game reached a QRR vs QR position, black was two pawns up but the its king's safety was worth the material. The game was adjudicated 20 moves later after the engines exchanged queens.

In game 16 Stockfish pushed pawns in the center and its eval stared to increase early. On move 12 Leela predicted the next 18 plys and its eval stayed constant. Stockfish opened the h file and castled long while Leela captured two pawns and opened the center. Stockfish surprised Leela on move 22, after more than 10 minutes thinking Leela's eval dropped almost to 0. The engines continued with a PV agreement of 25 plys. Leela's eval jumped over 2 after another long think, Stockfish chased the black king to the center and then reduced to a RR vs RN position. Stockfish continued to chase the black king until it was trapped on the a file.

The endgame was very slow. On move 51 Leela captured the white f pawn and created connected passers, but this allowed Stockfish to move a second rook forward on the queen side. A mate threat forced Leela to exchange a pair of rooks. Stockfish created a passer on the queen side, queened and mated. Stockfish wins the game pair, it leads 3-1.

Games 17-18 started with a 20-ply line in the Nimzo-Indian defense, Kmoch variation. In game 17 Stockfish pushed pawns on the queen side, opened the a file and created connected passers. The engines exchanged a pair of rooks, Leela had a passer in the center and evals gradually increased. Leela's eval jumped over 2 despite the advancing black passers that trapped a bishop on the back rank.

Leela blocked the black passers with a knight on c3 and then exchanged queens. Leela pushed pawns on the king side and Stockfish gave a pawn to break the pawn line. After exchanging a pair of knights the game reached a RBB vs RBN position, Leela brought its king to c3 to block the black passers. The trapped white bishop was still trapped but both evals were high at this point.

Leela captured both black passers and connected a second passer in the center. The trapped bishop became free to move, Leela used it to pin the knight and then capture it. The game ended in a tablebase win.

In game 18 Stockfish immediately played a4 after book to stop any advancing pawns on the queen side. Stockfish pushed pawns on the king side and gave a pawn. Leela was not impressed but was surprised by Stockfish's move 22.

Leela expected an exchange on f5, instead Stockfish exposed the black king, Leela thought for 10 minutes and its eval jumped to 1.5. The black king moved toward the center and Stockfish opened the e file. The white major pieces threatened the black king, in a series of exchanges the engines reduced to a Q vs RN position on move 41.

Stockfish captured pawns and saw the win in its PV. The white king moved forward to support the passers, Leela lost material and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 4-2.

Games 19-20 started with a line in the Caro-Kann advance, Short variation, played in high level human games. In game 19 the center was blocked and the engines exchanged minor pieces. Leela pushed the h pawn forward and Stockfish castled long. Leela opened the h file and the engines exchanged a pair of rooks, Stockfish's eval dropped and the game reached a BB vs BN position. The engines started to shuffle and the game was adjudicated.

In game 20 the engines started similarly, though Stockfish kept its king side pawns back. Leela castled long and Stockfish opened the center, it thought Leela's move 21 was inaccurate and its eval jumped. In a long PV agreement the engines reduced to a Q vs RR position, Leela's eval was still close to 1.

The endgame was slow, Stockfish's eval increased steadily and Leela's eval followed more slowly. Stockfish pushed pawns on the king side and created a passer, then slowly pushed it to the 7th rank. Leela created a passer on the queen side but it was too slow. The white king moved forward, Stockfish lost the passer but captured the pawns in the center and created more passers. Leela lost one of the rooks and the game ended in a tablebase win. Stockfish wins the game pair, it leads 5-2.