Season 25 superfinal games 81-90

After 90 games Stockfish leads 24-19 with 47 draws. Leela won another game pair and Stockfish's lead is down to 5 wins. There were 4 drawn game pairs, in one of these there were two white wins. Stockfish hasn't won a game pair in the last 13 played, while Leela won 3. There are only 5 game pairs to go so Stockfish is the favorite to win the match, but Leela is still fighting.

Games 81-82 started with a 22-ply rare sideline in the KID, Petrosian variation. All pieces and pawns were on the board and the center was blocked. In game 81 the engines pushed pawns across the board, Stockfish gave a pawn and opened a hole in the pawn line on the king side. Stockfish placed a knight on f5 and Leela moved its king to the corner. Evals came down and there was a long series of exchanges that opened the center and queen side. The result was that Stockfish was down a knight for a pawn with connected passers on the king side. After some shuffling Stockfish gave a rook and a bishop and queened a passer. The game ended in check repetition. In game 82 the engines opened the f file and the a file, then exchanged a pair of rooks. Evals came down, after exchanging a pair of bishops the engines started to shuffle. On move 40 Leela pushed the g pawn forward until Stockfish captured it. The engines reduced to a QB vs QN position, evals were low and the game was adjudicated.

Games 83-84 started with a rare sideline in the KID Fianchetto variation. In game 83 the engines blocked the center, Stockfish opened the queen side and Leela pushed pawns on the king side. The white king walked to the king side without castling. Stockfish had two strong knights in the center, it placed its major pieces on half open files on both sides. However evals slowly increased. Leela pushed a pawn to h6, then captured a pawn and created a passer on the queen side.

Leela exchanged a pair of knights, its passer shifted to the b file. With rook support Leela pushed the passer to the 5th rank where it was blocked. Stockfish doubled rooks on the f file, attacking the f3 pawn and trying to prevent it from moving forward. Leela captured one rook for a bishop, then threatened the back rank from the open c file. Stockfish blocked the c file and opened the way for the white passer to advance. Stockfish was desperate, it gave the second rook for a bishop to block the f pawn.

Stockfish quickly lost more material, Leela queened and mated.

In game 84 the engines blocked the center but there were no pawn exchanges after the start, only a few minor piece exchanges. Stockfish walked its king to the queen side, all files were blocked except the b and f files and the engines started to shuffle. Leela's eval dropped to 0, Stockfish couldn't find any safe way to move past the pawn lines. Pawn moves and captures reset the 50-move counter on moves 36, 83, 128, 175 (Stockfish gave a pawn), 204, 252 (Leela gave a pawn), 301 (knight exchange), 310 (Stockfish gave a pawn), and 329. The game finally ended on move 379 in a 50-move draw, after approximately 350 moves of nothing. This is a new TCEC record for most moves in a game. Leela wins the game pair, Stockfish leads 23-18.

Games 85-86 started with one of the main lines in the Czech Benoni defense, the center was blocked and all pieces and pawns were on the board. In game 85 there was one pawn exchange on the king side and Leela's eval started to increase. Stockfish captured a pawn, the engines played a long PV agreement and Leela's eval slowly came down. Stockfish gave back the pawn and Leela went a pawn up, then in a series of exchanges the engines reduced to a same color bishop ending. Leela wouldn't lower its eval for a long time, the engines shuffled and exchanged a few pawns. The game was adjudicated on move 118. In game 86 there were no exchanges after the start, the engines exchanged a pair of knights and mostly shuffled behind their pawn lines. On move 43 the engines exchanged a pair of bishops, then Stockfish captured a pawn but there was a stable pawn wall across the board. The engines shuffled for a long time, the 50-move counter was reset on moves 98 (knight for rook trade), 143, 182 (Stockfish gave a pawn), 224 (Stockfish gave another pawn), 233, 247 (queen exchange). On move 297 the game finally ended in a 50-move draw. Another long game with nothing happening.

Games 87-88 started with a rare sideline of the English symmetrical variation. In game 87 Stockfish exchanged minor pieces and its queen moved forward on the queen side. Stockfish captured two pawns and created 3 connected passers. Leela captured one passer and pushed its center pawns, Stockfish gave a rook for a bishop to protect its king. Stockfish pushed its passers forward, after exchanging queens the game reached a RB vs BN position on move 38.

Stockfish gave up the d and h pawns quickly, but it protected the others and Leela had a hard time trying to improve. The engines shuffled and evals drifted down. On move 65 Leela exchanged a pair of pawns on the king side, Stockfish's eval jumped.

The game was far from over but evals started to increase. Leela slowly moved its king to the center. The black king moved to the queen side and on move 85 Leela captured the black e pawn. The white f pawns became doubled passers, Leela slowly pushed them forward. Eventually Leela queened and the game ended in a tablebase win on move 121.

In game 88 the engines repeated game 87 for 20 plies, Leela captured one pawn on the queen side but Stockfish protected the second one. Stockfish regained the pawn and exchanged a pair of rooks, its eval started to increase. Leela captured the second pawn on the queen side and created two passers there but Stockfish captured one of them. After exchanging queens Stockfish gave a rook for two minors and reduced to a BB vs R ending. 

Stockfish exchanged a pair of pawns on the king side and created a 3 vs 1 pawn majority in the center. Its eval showed a clear win while Leela's eval increased very slowly. Leela pushed its passer and eventually captured a bishop for it. Stockfish slowly pushed the pawns forward, making sure the black rook couldn't stop them. It finally queened a passer on move 81, mating a few moves later. There were two white wins in this game pair, Stockfish leads 24-19.

Games 89-90 started with a 24-ply rare sideline in the Benoni classical variation, Czerniak defense. In game 89 after one move the engines started to play out a very long PV agreement. Stockfish gave a bishop and opened files on the king side. There was a threat to the white king, Leela gave back the piece and reduced to a RN vs RB position with white a pawn up. Stockfish's eval dropped, the engines traded pawns and then the rooks were exchanged. Leela wouldn't lower its eval for a long time, the game was adjudicated on move 92. Game 90 started with a 30-ply repeat of game 89. The game reached the same RN vs RB position, the engines traded pawns and Leela lowered its eval for an early adjudication on move 49.

Season 25 superfinal games 71-80

After 80 games Stockfish leads 23-17 with 40 draws. Leela won a game pair and reduced Stockfish's lead to 6 wins. The other game pairs were draws, with 3 having two white wins. Stockfish hasn't won a game pair for 8 straight pairs played, while losing 2. There is still hope for Leela, though it may be too late since there are only 10 game pairs left in the match.

Games 71-72 started with a rare sideline in the Nimzo-Dutch, Alekhine variation. In game 71 there were a few minor piece exchanges and the engines opened the d file. Stockfish gave a pawn, the engines exchanged a pair of rooks and evals were mostly stable. On move 28 the engines opened the a file.

Evals started to increase though the engines seemed to be shuffling. Leela gave two pawns on the queen side and captured a rook for a bishop. Leela then captured the two black pawns on the queen side, it was a pawn up in a QRB vs QBN position and evals were high.

Stockfish tried to avoid exchanges, Leela pushed the h pawn and it became a passer. Stockfish lost a bishop and captured the passer, it saw mate in its PV. Leela took a longer route, in the end a series of exchanges resulted in a tablebase win.

In game 72 more pieces stayed on the board, a pawn exchange opened the a file and evals came down. After some shuffling the engines opened the queen side and Stockfish went a pawn up. Stockfish traded its queen for a rook and a bishop, the engines reduced to a RBN vs QN position with white a pawn up. After 20 moves the engines traded minor pieces, when evals were low enough the game was adjudicated. Leela wins the game pair, Stockfish leads 20-14.

Games 73-74 started with a rare sideline in the Old Indian defense, normal variation. In game 73 the engines locked the center and there were no exchanges after the start. Leela offered a bishop and Stockfish refused to weaken its king. The engines opened the c file and exchanged a pair of knights, Leela captured the g7 pawn, then Stockfish captured two pawns on the king side. The black king looked vulerable, Stockfish exchanged queens and evals started to increase. The game reached a RRB vs RRB position on move 40.

After a pawn exchange on the queen side all the black pawns were isolated. Leela protected its d5 pawn with the bishop and started capturing black pawns. Stockfish held on to its a pawn, Leela pushed passers and moved its king forward. Stockfish lost material trying to stop the passers, the game ended in a tablebase win.

In game 74 there was one pair of pawns exchanged after the start, all files remained closed. The engines mostly shuffled behind their pawn lines but evals slowly increased. A pawn exchange on move 32 created passers in the center for both engines, on move 35 the first minor pieces were exchanged. Stockfish captured the doubled black passers in the center by move 42.

Leela had some initiative, its rooks controlled open files in the center. Leela attacked the exposed white king with a rook and queen, it also captured pawns on the queen side. Stockfish sent a rook and queen to attack the black king, it gave a rook for a bishop but then Leela had to give a rook to avoid mate. Both engines pushed passers forward, Stockfish queened first and mated. There were two white wins in this game pair, Stockfish leads 21-15.

Games 75-76 started with a 24-ply sideline in the Sicilian accelerated Dragon, Modern variation. White pushed pawns on the king side and its king was uncastled in the center, black had an eval advantage. In game 75 the engines played out a long PV agreement, pawn exchanges opened the center and king side, most pieces were exchanged and the game reached a RBN vs RBN position. Stockfish had a passer in the center, evals came down as Leela blocked the passer and kept its pieces safe. Leela gave a rook for a bishop, all pawns were captured and the game was adjudicated. Game 76 repeated game 75 for 39 plys, reaching the same RBN vs RBN position. Stockfish kept its pawns safe and blocked the black passer. The engines reduced to a rook ending, evals came down and the game was adjudicated.

Games 77-78 started with a 22-ply line in the Ruy Lopez, Arkhangelsk variation, played in high level human chess. All pieces and pawns were on the board and the black king was in the center uncastled. In game 77 Stockfish castled long and tried to attack the king side but was not strong enough. Leela's eval started to increase, it opened a file in the center and exchanged minor pieces. In a long PV agreement Stockfish's eval came down and then jumped up, Stockfish created a passer in the center while Leela captured a pawn and created an advanced passer on the king side. After another pawn trade Leela cleared all the black pawns on the king side and added 2 more connected passers.

In another long PV agreement each engine blocked an advancing passer and eventually captured it. The minor pieces were traded, on move 50 the queens were exchanged and the game reached a double rook ending with white a pawn up and two passers on the king side.

Leela pushed the passers slowly forward, Stockfish captured one while Leela captured a pawn on the queen side. Stockfish blocked the passer on the 6th rank and Leela captured another pawn and created a passer on the queen side. Leela pushed both passers to the 7th rank, Stockfish couldn't stop a queening and the game ended in a tablebase win.

In game 78 Leela was more active in its king side attack, it moved its queen to h3 and forced Stockfish to weaken the pawn support for its king. Stockfish ignored the attack, it opened the a file and moved its queen to the queen side. Leela gave a pawn, chose not to take the knight Stockfish offered and added a second rook to the attack.

Stockfish moved the queen to the king side, Leela captured the h pawn but that was the end of its attack. Leela's queen side seemed solid, yet evals continued to increase. Stockfish exchanged queens and a pair of bishops, then after a while it traded a rook for a knight and captured a pawn. The game reached a RNN vs RRB position.

Leela had a material advantage, but the white knights were very strong together and covered many squares. Stockfish exchanged pawns and created a passer in the center. Leela captured two pawns but lost the bishop, it gave a rook for a knight but couldn't stop the white passer queening, mate followed a few moves later. There were two white wins in this game pair, Stockfish leads 22-16.

Games 79-80 started with a rare sideline in the Queen's Indian defense, Kasparov-Petrosian variation. In game 79 the engines opened files with pawn exchanges in the center and queen side. Leela went a pawn up and exchanged queens, then it captured another pawn. In a series of exchanges Leela traded a rook for two minor pieces and the game reached a RB vs BBN position on move 30.

Leela pushed its two passers forward, Stockfish captured one but lost a bishop. Stockfish blocked the other passer with the knight, Leela had a very hard time trying to improve its position. On move 56 Leela captured a pawn, on move 73 it gave a pawn and then the black knight moved. Leela captured a pawn, only on move 88 it managed to push its passer forward. Stockfish saw a quicker win, but eventually it started to lose material and the game ended in a tablebase win on move 105.

In game 80 Stockfish pushed the h pawn forward and it was exchanged on h6, Leela castled short despite this and Stockfish kept its king in the center. Leela pushed pawns and opened the queen side, the engines exchanged minor pieces in the center. Stockfish's eval started to increase while Leela's eval was stable and even decreased a little.

The engines seemed to shuffle for a while, though Stockfish's eval steadily increased. After move 38 Leela's eval reacted as well. Stockfish blocked the center with its major pieces, on move 51 it exchanged a pair of rooks and reduced to a QRB vs QRB position.

Stockfish exchanged its b pawn and moved its queen to the back rank. It captured the black d pawn and exchanged bishops, seeing the win far in its PV. After exchanging queens the white king moved forward on the king side. Stockfish was only one pawn up, but after exchanging a pair of pawns it had a pawn majority in the center. Leela had a passer but the white king blocked it long enough until it captured the black e pawn. The white passers were faster and the black king was trapped, the game ended in a tablebase win before mate. There were two white wins in this game pair, Stockfish leads 23-17.

Season 25 superfinal games 61-70

After 70 games Stockfish leads 20-13 with 37 draws. Stockfish's lead is 7 wins after each engine won a game pair. There were 3 drawn game pairs, two had two white wins. Leela game pair win came after 17 game pairs which were either drawn or Stockfish wins. Leela almost won a second game pair, but an inaccuracy late in game 70 gave Stockfish the win and the game pair was drawn.

Games 61-62 started with a sideline of the QGD, Semi Slav defense, with the black king uncastled and the black queen on h6. In game 61 evals increased quickly after the start, Stockfish kept its king in the center and Leela forced it to move. Leela moved a knight forward and traded it for a rook.

Leela pushed pawns on the queen side, after some shuffling Leela captured a pawn on the king side and created a passer. The white queen moved forward on the queen side and captured two pawns, creating a passer there as well. Leela gave a pawn and add two more connected passers on the queen side.

Stockfish lost a bishop for two of the passers, Leela gained more material and mated.

In game 62 Stockfish pushed pawns in the center, it traded a rook and a pawn for two minor pieces. The black queen captured a knight and walked into a trap, Stockfish captured the queen for a rook. The game reached a QBN vs RRB position on move 25.

Leela was two pawns up, it doubled rooks on the open e file and its eval drifted down. Stockfish's eval steadily increased, it pushed pawns on the queen side and on move 41 exchanged a pair of pawns. Leela's eval started to increase as well, by move 56 the white queen captured two pawns and opened the queen side.

Leela pushed its passer to the 2nd rank, Stockfish traded its queen for the two black rooks and stopped the passer. The game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 18-11.

Games 63-64 started with a 20-ply sideline in the QGD, Albin counter-gambit, white was a pawn up and black had a passer in the center. In game 63 there was a long PV agreement after the start, the engines exchanged minor pieces and Leela captured the black passer. Evals came down, after exchanging queens the game reached a RRB vs RRB position. Stockfish slowly captured the pawns back, the engines reduced to a rook ending. Leela had a passer but it couldn't push it beyond the 6th rank. The game was adjudicated when Leela lowered its eval for the draw rule. 

In game 64 Stockfish pushed pawns on the queen side and captured the black passer. On move 20 Leela played h6, this weakened the black king and Stockfish's eval jumped. Stockfish attacked the king side with its queen and a knight, Leela gave a rook for the knight, Stockfish sacrificed another knight to expose the black king. Leela was forced to trade its queen for a rook to save its king from mate. On move 29 there was an imbalance of Q vs BBN on the board with high evals.

Stockfish ignored the black passer and continued to attack with its queen and rook. After exchanging rooks Stockfish captured the black passer. Stockfish pushed a passer on the king side, Leela lost a bishop for it. The white king moved forward and Stockfish mated. Stockfish wins the game pair, it leads 19-11.

Games 65-66 started with a 22-ply sideline in the Sicilian Taimanov, Szen variation, that appeared in a Fischer-Taimanov game. Both kings were uncastled, black had a strong knight on d4 as well as an eval advantage. In game 65 Stockfish grabbed the g pawn with a rook, this gave Leela time to improve its piece arrangement. Leela drove the black knight on d4 away, both kings moved forward and evals came down. The engines exchanged all rooks through the open g file and reduced to a QB vs QN position, evals were low and the game was adjudicated early on move 36.

In game 66 Leela also grabbed the g pawn as in game 65. The pieces stayed on the board longer, Stockfish moved a knight to d5, it drove the black knight from d4 and Leela moved it to c5. Stockfish castled long and (negative) evals started to increase. Leela managed to exchange the knights in the center, after queens were exchanged the game reached a RBN vs RBB position on move 40.

The engines blocked the queen side, Stockfish walked its king to the king side and pushed the h pawn forward. Leela exchanged pawns and got rid of the white e pawn, suddenly it was 3 pawns against 1 on the king side. Leela hid its king behind the white passer and shifted the rook to the queen side. The black rook moved to the 2nd rank and trapped the white king.

Leela captured the white h pawn, then gave a pawn to get the white f pawn out of the way. Leela pushed pawns on the king side and Stockfish lost pieces trying to avoid mate. Stockfish raced to queen a passer but was mated on the other side. Leela wins the game pair, Stockfish leads 19-12.

Games 67-68 started with a rare sideline of the KID, four pawns attack. In game 67 the engines opened the d file, a black knight made an unusual journey of 5 moves and was traded for a bishop. In a series of exchanges the engines reduced to a RRB vs RRB position and evals came down. Leela doubled rooks on the d file, after a few pawn exchanges the engines started to shuffle. After 40 moves Leela exchanged a pair of rooks and the game was adjudicated. In game 68 the engines opened the d file and also the b file, Stockfish moved its king forward without castling. The white queen moved forward, in a long PV agreement there were many exchanges and Stockfish gave a rook for a bishop. For a few moves Stockfish's eval jumped, then unexpectedly dropped back even though it anticipated Leela's move. Stockfish regained a rook for a bishop, after exchanging queens the game reached a rook ending. Stockfish was up a pawn with a passer, Leela gave a pawn and as a result all the white pawns were isolated and a pair was doubled. Leela held the draw, though it wouldn't lower its eval for a long time

Games 69-70 started with a rare sideline of the Pirc defense, Austrian attack. In game 69 Leela attacked the king side, the engines exchanged minor pieces and Stockfish was a pawn up but the black king was vulnerable. After a few pawn moves and some shuffling Stockfish moved its queen to a3, perhaps to attack the unguarded b3 pawn.

Leela thought this was a mistake and its eval jumped, Stockfish's eval reacted only 3 moves later. Leela attacked the black king and Stockfish quickly moved its queen back to help. Leela regained the pawn, after exchanging queens it created a passer on the queen side. Then it captured two more pawns and reduced to a RN vs RB position.

While Stockfish focused on the white a passer Leela managed to capture the last black pawn and create passers on the king side. Leela pushed passers forward, Stockfish stopped one before the game ended in a tablebase win.

In game 70 there were early exchanges, the engines opened the f file and exchanged a pair of rooks. The game reached a QRB vs QRN position on move 20, there were a few pawn moves and the engines started to shuffle. On move 74 the engines opened the a file and shuffling resumed, evals drifted down and the game seemed to be heading for a draw.

Stockfish thought Leela's move 89 was an inaccuracy and its eval started to increase, Leela's eval increased as well. Both engines were low on time and played in blitz mode. Stockfish managed to double rook and queen on the a file, then moved its rook forward and exchanged rooks. The white queen moved forward and used a mate threat to capture a pawn and create a passer. Stockfish blocked Leela's attempt to counter attack, then it captured a second pawn.

Stockfish exchanged queens, Leela managed to regain the two pawns including the passer on the queen side. However, the black king was too far to defend the isolated pawns on the king side, Stockfish captured two pawns, queened and mated. There were two white wins in this game pair, Stockfish leads 20-13.

Season 25 superfinal games 51-60

After 60 games Stockfish leads 17-10 with 33 draws. Stockfish extended its lead to 7 wins after another game pair win. There were two game pairs with two white wins. After 30 game pairs Leela still has only one game pair win. Stockfish won 5 of the last 15 game pairs.

Games 51-52 started with a rare 20-ply sideline in the KID Fianchetto, classical main line. In game 51 there was one pair of pawns exchanged after the start, the engines played behind their pawn lines for a long time. The first piece exchange was on move 32, afterwards there were a few pawns and minor pieces exchanged. On move 45 Stockfish's eval dropped, it gave a rook for a bishop and three pawns, then reduced to a QR vs QN position. Leela managed to capture 3 pawns back, its eval slowly came down and the game was adjudicated.

In game 52 Leela locked the center early, there was one pawn exchange on the queen side and the engines started to shuffle. Stockfish extended the shuffle beyond move 80 with pawn moves. Evals slowly started to increase, on move 88 Leela pushed the f pawn.

Both engines were low on time and played quickly. After a few moves Stockfish opened the king side, evals increased rapidly as the engines exchanged pieces and pawns. On move 106 the game reached a R vs NN imbalance with white two pawns up.

Stockfish captured another pawn and it had 3 passers on the queen side. Leela lost material quickly, Stockfish queened and mated. Stockfish wins the game pair, it leads 15-8.

Games 53-54 started with a rare sideline in the KID Saemisch, Yates defense, played in high level human chess. In game 53 the engines blocked the center and Leela castled long. Stockfish gave a pawn on the king side, giving Leela a passer and hiding its king behind it. Leela gave a knight for two pawns to open the king side and evals dropped. In a series of exchanges the engines reduced to a RR vs RBN position, white two pawns up. Leela still had 7 pawns, its rooks were not effective and the engines shuffled. Leela gave two pawns and captured a knight, evals were low enough and the game was adjudicated. In game 54 Stockfish opened the d file and captured a pawn, queens were off early and evals came down slowly. The engines shuffled for a long time, Stockfish moved a pawn to reset the 50-move draw counter, Leela pushed a passer to the 2nd rank. Stockfish captured another pawn and gave a rook for a knight, the game reached a BN vs RN position with low evals and was adjudicated.

Games 55-56 started with a rare sideline in the Nimzo-Indian defense, three knights variation. In game 55 a series of exchanges opened the center. Stockfish kept its king uncastled and Leela forced it to move, blocking the king side rook. Evals came down after most minor pieces were exchanged, on move 29 the game reached a QRR vs QRR position. Stockfish freed its trapped rook, Leela traded its two rooks for the black queen. The engines traded pawns, Leela was a pawn up but Stockfish held the draw. The game was adjudicated when Leela lowered its eval for the draw rule. Game 56 started similarly with small variations, again the black king side rook was trapped. Leela developed the rook through the h file. There was a lot of shuffling and some pawn and piece exchanges, evals came down. On move 53 the engines reduced to a Q vs RR position. Stockfish was two pawns up but not enough to win, the game was adjudicated when Stockfish lowered its eval for the draw rule.

Games 57-58 started with a rare 22-ply sideline in the Ruy Lopez closed variation. In game 57 the center was blocked and there were no exchanges after the start. Evals slowly increased, Leela pushed pawns on the king side, after move 28 there were a few pawns and minor pieces exchanged and Leela placed a pawn on h6. 

Queens were exchanged, more pawn exchanges opened the board. On move 50 Stockfish gave a rook for a bishop and the white h pawn, the game reached a RRN vs RBN position. Stockfish was a pawn up with connected passers on the king side, but Leela had a significant eval advantage.

The black passers were too far behind to be a threat. Leela captured the a pawn and pushed two passers forward. Stockfish lost material trying to prevent a queening, Leela queened a pawn in the end and the game was adjudicated before mate.

In game 58 again the center was blocked, this time Leela chose to open the b file with the first pawn exchange. Evals were stable, there were no other exchanges and the focus shifted to the king side. After some preparation Stockfish doubled rooks on the f file and on move 39 it pushed the f pawn forward.

Stockfish expected f6 and opening the f file, Leela chose to take with the g pawn. Stockfish took back with its knight and allowed Leela to take the knight. Stockfish thought these Leela moves were inaccuracies and its eval jumped, Leela's eval also jumped a move too late. The king side opened with the white major pieces attacking the black king. Leela gave a bishop back and exchanged pieces, on move 58 the game reached a QBN vs QR position. 

Both kings were exposed but Stockfish found safe squares for its king and slowly moved it forward. Stockfish captured a pawn and exchanged queens, then pushed a passer forward. Leela tried a stalemate trap, Stockfish captured the black rook and promoted the passer to a knight, then mated with minor pieces. There were two white wins in this game pair, Stockfish leads 16-9.

Games 59-60 started with a sideline of the Ruy Lopez, Bird defense variation. In game 59 both queens moved forward early, Leela forced the black king to move without castling. There were many early exchanges and the game reached a RB vs RN position with white a pawn up on move 26.

Leela thought Stockfish should have taken the rook with its king on move 26, its eval jumped and it offered a rook exchange. Stockfish's eval jumped as well and it refused the offer. Leela had a pawn majority on the king side, after a pawn trade it shifted to a pawn majority on the queen side. The white king slowly moved forward to assist, on move 57 Leela captured another pawn and created connected passers.

Leela pushed its passers forward, the white king switched to the king side and captured a pawn. Stockfish lost a rook for one passer, Leela queened and mated.

In game 60 the white queen moved forward on the king side, Leela castled short despite the threat. Stockfish pushed the f pawn forward and evals increased. The engines exchanged all bishops, Leela stopped the white pawn on f6 and exchanged queens. Only RRN vs RRN were left on move 27.

By the time Leela activated its queen side rook Stockfish moved both rooks forward, then captured the h pawn and created a passer. The engines traded pawns and exchanged a pair of rooks, Stockfish captured another pawn on the queen side and created a passer there. By move 56 all the black pawns were gone, Stockfish was two pawns up in a RN vs RN endgame. 

Stockfish moved its king forward and pushed its pawns slowly. Leela tried to avoid a 7-man position, this only prolonged the game for a few moves before adjudication. There were two white wins in this game pair, Stockfish leads 17-10.

Season 25 superfinal games 41-50

After 50 games Stockfish leads 14-8 with 28 draws. Stockfish extended its lead to 6 after two game pair wins. There were 3 drawn game pairs, one of them with two white wins. Stockfish won twice in a queen endgame, Leela seems to be struggling in these, its eval is sometimes low when Stockfish already sees the win in its PV. At the half way point of the match Stockfish is leading by 6 wins, not a huge margin after 25 game pairs played. However so far Leela only won a single game pair, so I would say Stockfish is the clear favorite to win the match.

Games 41-42 started in the Scandinavian defense, Mieses variation, played in high level human chess. In game 41 the engines played out a long PV agreement, the black king moved without castling and white castled long. Evals were stable, most minor pieces were exchanged, Stockfish developed its king side rook through the h file. On move 29 the game reached a QRR vs QRR position.

The engines pushed pawns forward and evals started to increase. After a pawn exchange both engines created a passer on the queen side. All the pieces focused on the black e5 pawn, on move 57 the queens were exchanged.

Stockfish gave the e pawn, perhaps to activate its rooks. Leela catured another pawns and pushed two passers forward. Stockfish blocked the passers with its rooks and pushed its passer forward. Leela captured a rook, both engines queened, Leela had the material advantage to force mate.

In game 42 the engines repeated game 41 for 40-plys, this time Stockfish did not exchange its last knight. The engines shuffled for a while, then Stockfish moved the g pawn forward and captured a pawn. Evals started to increase, in a series of exchanges the engines reduced to a double rook ending.

All pawns were passers, Stockfish blocked a captured the black e pawn on the 2nd rank. It had two passers left, with the king support it slowly pushed them forward. Leela tried to avoid a 7-man position but Stockfish forced it when it queened a passer and Leela captured it. There was one white pawn left, the engines continued to play the won 7-man position for more than 30 moves, the game reached a tablebase win on move 135. There were two white wins in this game pair, Stockfish leads 12-8.

Games 43-44 started with a 22-ply rare sideline of the QGD Orthodox defense, Rubinstein variation. The engines castled in opposite directions, all pieces were on the board and the c file was open. In game 43 after a few moves the engines started a long PV agreement, they exchanged queens and a few minor pieces. Evals came down, Stockfish gave two pawns and the game reached a RB vs RB position. Leela was two pawns up with two doubled pawns, Stockfish had an advanced passer and also had a possibility of perpetual check. Evals were low enough for an early adjudication. 

In game 44 Leela pushed pawns on the queen side and placed a rook on the open c file. Evals slowly increased, Stockifsh pushed pawns on the king side. In a long PV agreement Leela gave a pawn, opened the queen side further and the black queen joined the attack.

Stockfish made sure it had enough pieces to defend b2. After exchanging a pair of rooks Leela's attack appeared less threatening. The engines continued to exchange pieces and reduced to a QB vs QB position on move 47. The white king slowly moved forward, the bishops were exchanged on move 59.

Stockfish captured the black b pawn, Leela chased the white king with its queen for a long time. Leela's eval dropped below 1 for a while but then jumped back. On move 102 the white king reached the back rank, Leela started to lose pawns, Stockfish managed to queen a passer and mate. Stockfish wins the game pair, it leads 13-8.

Games 45-46 started in the KGA Bishop's gambit, Cozio variation. Black was a pawn up, the white king moved without castling and black had an eval advantage. In game 45 the engines developed their pieces, then Stockfish gave two pawns, opened the e file and placed a pawn facing the white king on the king side. Leela's (negative) eval jumped, Stockfish captured a pawn back and castled long. In a long PV agreement Leela's eval dropped back, the engines exchanged pieces and pawns until only QR vs QR were left on move 36.

Leela gave the d pawn, its eval was stable while Stockfish's eval steadily increased as it chased the black king to the center. On move 48 the rooks were exchanged, after a while the black h pawn became a passer after a pawn trade. Leela's eva; continued being low, below -0.5 at times as the game progressed. In some of the moves Leela spent a lot of time thinking, yet its eval did not reflect what Stockfish saw as a clear win. On move 76 Stockfish's eval was already over -95, Leela's eval was -.059.

Leela's eval slowly increased finally when Stockfish was already predicting a 7-man win. On move 94 Stockfish captured a pawn, a frew moves later it queened the passer, then it forced mate.

In game 46 Leela castled long early and Stockfish attacked the queen side. Stockfish's (negative) eval dropped, it gave a knight for two pawns and exposed the black king. Leela had to walk its king back to the center and Stockfish pushed a passer to the 7th rank. The black king continued to run to h6, Leela's eval dropped as well and Stockfish pushed a second passer on the queen side. Leela lost a rook for one passer, Stockfish gave a rook for a knight on the king side and exposed the black king to checks again. Evals were low enough and the game was adjudicated. Stockfish wins the game pair, it leads 14-8.

Games 47-48 started with a 23-ply line in the QGD exchange variation. The engines castled in opposite directions, there was only one pair of pawns exchanged, black had an eval advantage. In game 47 Stockfish went a pawn up, (negative) evals came down while the engines exchanged pieces and pawns. On move 28 the game reached a RRB vs RRB position, Leela regained the pawn. Evals were close to 0, after exchanging a pair of rooks the game was adjudicated. In game 48 Leela went a pawn up and pushed pawns on the queen side. Again evals came down as the engines exchanged pieces and pawns. Stockfish regained the pawn, the game reached a QB vs QN position and was adjudicated.

Games 49-50 started with a 20-ply line in the Robatsch (modern) defense. There were no exchanges and white castled long. In game 49 the engines developed pieces and Stockfish castled long as well. Evals came down as the engines played out a very long PV agreement, several pawns and pieces were exchanged and Leela went a pawn up. After the PVs diverged the engines reduced to a QR vs QR position, Stockfish regained the pawn and it had a passer on the king side. The engines shuffled, Leela wouldn't lower its eval, perhaps since the black king was exposed. It lowered its eval with less than 10 moves left on the 50-move counter, the game was adjudicated. Game 50 started with a 53-ply repeat of game 49. After the PVs diverged Leela regained the pawn, the engines shuffled for a while and then reduced to a RN vs RB position. White was again a pawn up but evals were low and the game was adjudicated.

Season 25 superfinal games 31-40

After 40 games Stockfish leads 11-7 with 22 draws. Stockfish extended its lead to 4 wins after winning two game pairs, three game pairs were drawn, one of which had two white wins. In the two game pairs Stockfish won it displayed superior endgame skills. In one game pair the two games reached exactly the same RB vs RB endgame, Stockfish managed to draw as black and win as white. In the other Stockfish won a queen ending which Leela seemed to think was a draw for a long time.

Games 31-32 started with a 24-ply line in the Ruy Lopez, Open, classical defense, played at the highest level of human games. There was one pawn exchange and all pieces were on the board. In game 31 after two moves the engines started to play out a long PV agreement, exchanging most pieces and reducing to a RBN vs RBN position on move 21. Leela was a pawn up, its eval went up for a for a few moves but then came down. The engines traded pawns until all pawns were passers, 3 white on the queen side and 2 black on the king side. Evals were low, after exchanging more pieces the game was adjudicated. 

In game 32 Leela's first move was different, the black king was vulnerable and Stockfish placed a bishop on h6. The engines exchanged all knights in the center, Leela gave a pawn and both engines created a passer, evals started to increase slowly. Stockfish gave the pawn back, the engines exchanged a pair of rooks and Stockfish replaced the bishop on h6 with a pawn. In a series of exchanges the engines reduced to a queen ending with white a pawn up.

Stockfish used checks to improve its position while keeping its pawns safe. Leela's eval did not increase at first, it jumped when the white king moved forward. Stockfish saw the win in its eval, it forced a queen exchange on move 82, then it queened and mated. Stockfish wins the game pair, it leads 9-6.

Games 33-34 started with an 18-ply line in the Ponziani opening, Jaenisch counter attack. The white king side was exposed with the black queen on h3, black had the advantage. In game 33 Stockfish avoided a queen exchange, it castled long while the white king moved without castling. Leela was slow to develop the queen side, though (negative) evals came down. Stockfish created a passer on the king side and pushed it forward while Leela captured a pawn. Stockfish gave a knight and attacked the white king, Leela lost a rook for the passer and the game reached a B vs R ending. Both engines had two pawns on the queen side and Leela had a fortress. Stockfish wouldn't lower its eval for the draw rule, the game was adjudicated only on move 159. In game 34 Leela castled long, the queens were off early and the white king was not in danger. (negative) Evals came down, Stockfish captured pawns on the king side and gave a rook for a bishop. Leela created a passer on the king side and pushed it forward, Stockfish blocked with a rook. In a RBN vs RRN position Stockfish gave two minors for a rook and captured the black passer. Evals were close to 0 and the game was adjudicated. 

Games 35-36 started with a sideline of the Old Indian defense. In game 35 Leela moved its queen forward and captured the b7 pawn, Stockfish tried to trap the white queen. Leela moved a knight forward and captured a second pawn, then gave a rook for a bishop and moved its second knight forward to protect the first knight and to let the queen retreat. Evals came down, there were more exchanges and eventually the engines reduced to a QRB vs QRN position. After exchanging queens the game was adjudicated. In game 36 Stockfish moved its queen forward, it captured two pawns on the queen side and Leela didn't try to stop it. Stockfish exchanged queens, it was two pawns up but its development was slower and its king castled late. Leela moved a rook to the 2nd rank and in a RRB vs RRN position captured one pawn back. Evals came down, the engines continued to exchange pawns and pieces and the game was adjudicated in a rook ending.

Games 37-38 started with a 32-ply line in the Sicilian Dragon, Yugoslav attack. The engines castled in opposite directions, black was a pawn up and the h file was half open. In game 37 Stockfish gave a rook for a bishop early, then it gave another rook for a knight and exchanged queens. On move 29 the game reached a RR vs BN position with black 3 pawns up.

Stockfish tried to block files to restrict the white rooks, Leela gave a pawn and opened the queen side. Stockfish captured all the white pawns but Leela moved its rooks forward and captured pawns. Eventually Leela trapped and captured the black bishop, the game ended in a tablebase win.

In game 38 the engines exchanged bishops and Stockfish moved its queen to h6. The black king was trapped and Leela moved its queen to help it. Stockfish exchanged a pair of knights and regained the pawn, then the queens were exchanged. Stockfish captured another pawn and created a passer on the king side, on move 31 the game reached a RN vs RB position.

Leela blocked the passer with its king. In a long PV agreement the engines exchanged pawns and Stockfish abandoned its passer, though evals continued to increase. On move 51 the remaining pawns were on the queen side, each engine had 3 pawns, the black pawns were all on dark squares and the white pawns on light squares.

Two black pawns were weak and the bishop could not protect them. Stockfish made sure its b3 pawn had enough defenders, slowly it captured black pawns and on move 75 all were captured. Stockfish had two pawns, Leela lost material and the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 10-7.

Games 39-40 started with a 20-ply line in the Semi Slav, accelerated Meran variation. Both queens moved forward  on the queen side where a pair of pawns was exchanged. In game 39 the engines played out a long PV agreement, they opened files on the queen side, Stockfish kept its king uncastled. Stockfish gave two pawns and then in a series of exchanges the game reached a RB vs RB position. Leela was two pawns up with no passer and doubled pawns on the queen side. After a while Stockfish managed to captured one of the doubled pawns and formed a strong bishop-pawn pair on the queen side. Evals slowly came down while the engines shuffled, Leela couldn't find a way to improve. There were a few pawn exchanges, Leela was slow in lowering its eval, the game was adjudicated on move 112.

In game 40 the engines repeated game 39 for 72 plys, with transpositions and in some cases slightly different moves. The game reached a RB vs RB position with white a pawn up, and with such a long repeat and evals stable and not high it was obvious the game would have the same outcome. On move 53 Stockfish's eval jumped, but after a pawn exchange a few moves later it came back down. On move 73 Stockfish's eval jumped again, this time it kept increasing. Leela's eval remained low for more than 15 moves, the white king managed to move forward through the center and Stockfish created a passer on move 90.

Leela's eval started to increase while Stockfish already saw the win. Leela captured the two pawns on the king side but Stockfish threatened mate and Leela gave a rook for a bishop. The game ended in a tablebase win with one last white pawn. Stockfish wins the game pair, it leads 11-7.

Season 25 superfinal games 21-30

After 30 games Stockfish leads 8-6 with 16 draws. Stockfish's lead is still 2 wins after each engine won one game pair and there were three drawn pairs, one with two white wins. Leela won its first game pair of the match, adding tension to the match since it is not one-sided and the gap is still small. 

Games 21-22 started with 6-ply line in the Scandinavian, Blackburne gambit. In game 21 the engines played out a long PV agreement, developing their pieces and exchanging a few minor pieces. Leela had a pawn majority on the queen side but it didn't find a way to push the pawns safely. Evals came down, the engines shuffled for a long time. After exchanging pieces the draw rule adjudicated the game on move 79. In game 22 again the engines developed their pieces mostly in PV agreement, and most minor pieces were exchanged. Evals slowly came down, the game reached a QRN vs QRB position with white a pawn up. Stockfish gave a pawn and created a passer, after some shuffling it gave another pawn. Evals were close to 0, the engines continued to exchange pieces and the game was adjudicated.

Games 23-24 started with a 19-ply line in the Sicilian, Scheveningen variation, Keres attack, played in high level human chess. In game 23 the engines castled in opposite directions, in a knight exchange Leela chose to retake with a rook and Stockfish's eval dropped. Stockfish seemed to have the initiative, it was focused on attacking the queen side while Leela blocked and interfered. Evals steadily decreased, Stockfish managed to get a knight to a3 and to open files. It gave a rook for a bishop and moved the queen forward to attack the exposed white king. The game was adjudicated in a QR vs QN position, with perpetual check in the PV.

In game 24 again the engines castled in opposite directions, in the same knight exchange Stockfish retook with a bishop. For a few moves Stockfish offered a bishop and Leela refused to take as it would expose its king to attack. In a series of exchanges the engines reduced to a RBN vs RBN position, Stockfish was a pawn up with connected passers on the queen side but evals were low.

Leela moved its rook forward and captured a pawn, Stockfish's eval started to increase. Stockfish chased the black pieces away and attacked the black king. Leela's eval reacted after 6 moves, the black king had to run forward. After exchanging bishops Stockfish captured two pawns on the king side. Leela had a passer on the king side, Stockfish was only a pawn up but now both evals were over 2.

Stockfish blocked the black passer with its rook and slowly pushed its queen side passers. Leela traded its passer with the white f pawn, and pushed its e passer forward. Stockfish captured the passer with its knight on the 2nd rank, Leela did not take back to avoid a 7-man position. This only delayed the end by a few moves after Stockfish queened a passer. Stockfish wins the game pair, it leads 7-4.

Games 25-26 started with an 18-ply line in the Sicilian Nimzowitsch variation. Both queens were out on the queen side, white was a pawn up with a passer on d6. In game 25 Leela gave a pawn and Stockfish castled long. Stockfish captured the white passer but lost a knight. The engines played out a long PV agreement where the queens were traded and the result was a BN vs R imbalance with high evals.

Stockfish formed a pawn line on the king side and tried to protect the pawns, Leela exchanged a pair of pawns and captured one, creating a passer. After exchanging a pair of rooks Leela traded a knight for the black bishop, leaving a BB vs R ending.

Both engines had a passer but the bishop pair was very strong. Leela captured the black pawns on the king side and blocked the black passer. The white passers were unstoppable, the game was adjudicated after Leela queened.

In game 26 both kings stayed in the center and the black queen retreated. Stockfish lost its passer and it gave another pawn, giving Leela a passer in the center. Evals rapidly increased, Leela captured another pawn but lost a rook by a knight fork. 

Leela's compensation for the rook was the trapped knight in the corner as well as the white rook and bishop on the king side that could hardly move. Leela pushed the passer to d3 and tightened the trap. Stockfish captured the h pawn with its queen and freed its corner knight. It pushed the h pawn and opened a way out for its rook. In a series of exchanges the engines reduced to a RRB vs RB position. 

Leela had connected passers on the 2nd and 3rd ranks but they were blocked, and Stockfish had an extra rook. Stockish gave a rook for a bishop and captured both passers, the game ended in a tablebase win. There were two white wins in this game pair, Stockfish leads 8-5.

Games 27-28 started with a 20-ply sideline of the French, Tarrasch closed variation. In game 27 both kings stayed in the center and there were many early exchanges. Stockfish had a passer in the center, after exchanging queens Leela created a passer on the king side. Evals steadily decreased, Stockfish castled late and blocked the white passer with its king. The game reached a RBB vs RBN position, Stockfish captured the white passer and Leela moved the rook to the 7th rank. Evals were low enough for the draw rule, Stockfish gave a rook for a bishop and the game was adjudicated. Game 28 started with a 30-ply repeat of game 27 with a transposition. Stockfish pushed pawns on the king side and created connected passers there. Leela walked its king to block together with a knight, Stockfish traded a bishop for the knight and the game reached a RRB vs RRB position. The engines shuffled for a while with evals close to 0, after exchanging a pair of rooks the game was adjudicated.

Games 29-30 started with a rare sideline of the semi Slav, accelerated Meran variation. In game 29 the engines formed a diagonal pawn wall that blocked the center and most of the queen side. The engines castled in opposite directions and evals were stable. A few pawn exchanges opened the g file, most of the black pieces moved to the king side to protect the king. All pieces were on the board, the engines shuffled for a while and then Stockfish captured the h pawn on move 38.

With two open files on the king side Stockfish slowly walked its king to the center. Leela's eval increased and it captured the a pawn, Stockfish was less convinced but it had very little time left to think. The engines exchanged all major pieces, Leela captured another pawn and Stockfish tried to hold its position but its eval increased as well. Leela created an advanced passer on the queen side, the engines reduced to a BBN vs BNN position on move 73.

Stockfish's defense collapsed, Leela's pieces moved forward and it managed to capture the black pawns on the queen side. Leela was two pawns up, the white king moved forward and Stockfish couldn't stop the passers. Leela queened and mated.

In game 30 both engines castled short, instead of a pawn wall the engines exchanged pawns and opened the board. Evals came down, the engines exchanged pieces until the game reached a queen ending. Stockfish was a pawn up but with all pawns on the king side. Evals were low enough and the game was adjudicated. Leela wins the game pair, Stockfish leads 8-6.