Season 22 superfinal games 61-70

After 70 games Stockfish leads 22-7 with 41 draws. Stockfish won two more game pairs, KomodoDragon again couldn't hold as black and win its first game pair in its 7th attempt. 

Games 61-62 started with a Modern Averbach system variation, in both games the black king was forced to move early. In game 61 there were no pawn exchanges, evals were under 1 and remained constant as the engines exchanged minor pieces. KomodoDragon castled long but did not try to open the position, the engines shuffled for a long time. KomodoDragon avoided the 50-move draw and then the exchanges started and evals dropped to 0. The game was adjudicated in a RN vs RB position. In game 62 KomodoDragon gave an early pawn on the queen side, a minor piece exchange opened  afile in the center and the engines exchanged queens. Stockfish castled long while KomodoDragon walked with its king to the king side. Evals came down and in after a series of exchanges only RR vs RN remained. The white rooks came forward and captured two pawns, KomodoDragon attacked the white king. Stockfish avoided a perpetual check but lost a rook for a knight, the rook ending was a draw.

In game 63 there were no exchanges after book, the engines moved their pieces on the crowded board either preparing an attack or defending against something. Evals were around 1.5 and didn't change a lot. On move 26 KomodoDragon locked the center, and there was an exchange of knights. Stockfish tried to close the king side and KomodoDragon exchanged a pair of pawns to create a small opening. There was a period of shuffling, both engines moved their kings away from the king side, the white king walked all the way to the opposite corner. KomodoDragon's eval started to increase and on move 52 the eval jumped, KomodoDragon pushed the f pawn and was ready to open the position.

Stockfish was on increments and may have missed something, this move caught it by surprise and its eval jumped as well. KomodoDragon gave two pawns and broke through the center. The white major pieces moved to the center and the black king was in danger, the black pieces could only watch from the side. KomodoDragon then offered a rook in the center. 

Stockfish refused to take, exposing the king would lead to more trouble. Instead it gave two pieces and its queen tried to give checks. This only lasted for a short while, the material advantage was too great and the game ended in mate.

In game 64 again there were no exchanges after the start. Stockfish locked the center earlier and the white king stayed uncastled in the center. On move 23 a pair of pawns was exchanged on the king side, evals increased a little as Stockfish moved pieces there and threatened the black king. On move 38 another pawn exchange opened two files on the king side. The white king walked to the queen side, evals jumped when a file opened there and Stockfish took control of it after exchanging a pair of rooks.

KomodoDragon infiltrated through the king side, for a while Stockfish played defensively though evals continued to increase. Nothing came out of KomodoDragon's attack, on move 62 Stockfish went a pawn up.

Stockfish increased the pressure on the back ranks, eventually KomodoDragon exchanged pieces and was a piece down in a RBN vs RN position. Stockfish had too many advancing passers, KomodoDragon lost more material and the game ended in mate. There were two white wins in this game pair, Stockfish leads 20-7.

In game 65 the engines opened the center, and KomodoDragon created a central passer through exchanges. Stockfish developed its queen side pieces late, it managed to capture the passer and was a pawn up. A series of exchanged left a QRN vs QRN position, KomodoDragon moved a rook forward and regained the pawn. KomodoDragon had a pawn majority on the queen side, it even captured another pawn and created a passer. However evals dropped, the engines reduced to a queen ending and the game ended in a tablebase draw.

In game 66 again the engines opened the center, this time Stockfish gave a pawn and its queen came forward to create a central passer. On move 13 the engines entered a very long PV agreement, the queens were exchanged and KomodoDragon captured the passer. KomodoDragon captured pawns but lost a piece, evals started to increase and at the end of the PV agreement the game reached a BNN vs BN position with black 2 pawns up.

The engines traded pawns until there was only one white pawn and two black ones. Stockfish kept its king on the king side to keep an eye on the black passer, KomodoDragon moved its king to the center as an additional defender while the white pieces tried to use their numerical advantage. It took time to move the knights to the right squares and drive away the black king, eventually Stockfish was ready to capture the black pawn on the queen side.

Stockfish changed its mind in response to KomodoDragon's moves, instead of capturing the pawn it exchanged knights and cleared a path for its last pawn. KomodoDragon couldn't stop the passer without losing its bishop, eventually Stockfish queened and ended the game in mate. Stockfish wins the game pair, it leads 21-7.

In game 67 both engines castled long, there were a few minor piece exchanges and one pawn exchange that weakened the white pawn structure. Evals stayed around 1 and the engines mostly shuffled, the white king walked back to the center. On move 37 Stockfish opened the king side and created a passer. When KomodoDragon exchanged pawns on the queen side Stockfish's eval dropped, a series of exchanges reduced to a RR vs RB position. KomodoDragon thought it had an advantage but with one rook blocking the black passer it couldn't improve and just shuffled. Both evals dropped, after 30 moves the exchanges started. There was a pawn race and both engines queened, however the game ended in a tablebase draw.

In game 68 there were a few pawn exchanges in the center and the engines opened the c file. Stockfish kept its king uncastled in the center while KomodoDragon castled short. On move 24 the first pieces were exchanged and the engines started a long PV agreement. Evals increased after Stockfish placed a strong knight on d6 forking queen and rook. KomodoDragon escaped the fork but the knight restricted its movement. KomodoDragon grabbed a pawn on the queen side, it realized it was in trouble despite the small material advantage.

KomodoDragon gave back the pawn to open a diagonal for its LS bishop. The white king was exposed, the black queen moved forward and Stockfish exchanged queens. KomodoDragon was reluctant to exchanged the white knight since that would create an advanced passer for white. However after a while KomodoDragon did exchanged a bishop for the knight and then gave a rook for a bishop to capture the passer. 

The material advantage was small but KomodoDragon couldn't hold this position. Stockfish managed to capture the pawns on the queen side, then mate threats forced KomodoDragon to give pieces, game over. Stockfish wins the game pair, it leads 22-7.

Games 69-70 started with a 32-ply book in a closed Ruy Lopez, Flohr system, a line played at the top level of human chess. In game 69 there were only a few pawn moves after book, the position remained closed. There were a few minor piece exchanges and evals came down. The game was adjudicated while most pieces and pawns were still on the board. In game 70 KomodoDragon pushed pawns on the queen side, it gave a pawn and both engines created a passer. Stockfish gave a rook for a bishop, after a few exchanges KomodoDragon gave the material back. Evals came slowly down and the game reached a QRN vs QRN position. After exchanging queens evals were low enough for the draw rule.