Season 16 superfinal games 21-30

After 30 games Stockfish leads 4-2 with 24 draws. AllieStein lost another game with a blunder caused by ignoring a winning move by the opponent, as well as not thinking long enough before making a move. It immediately came back with a win, this time showing a better understanding of the position than Stockfish.

The engines castled in opposite directions in the book sequence of games 21-22. AllieStein started game 21 with an eval over 1 and it stayed at that level for a long time. Stockfish pushed pawns on the queen side and opened files facing the white king. After several exchanges only RRB vs RRB remained on move 25, white had a pawn majority on the queen side. AllieStein managed to create a queen side passer, other than that the engines mainly shuffled. The game was adjudicated when AllieStein lowered its eval. AllieStein pushed pawns on the queen side in game 22, this time the engines locked pawns and kept the queen side closed. Stockfish pushed pawns on the king side but couldn't open files there either. The engines mainly shuffled, after the last knight was off Stockfish captured a pawn but could not improve. The game ended in a 50-move draw.

There were no exchanges after the start in game 23, the first exchange occured on move 22. The engines continued to play mostly behind the pawn lines, on move 39 the last knights were exchanged and evals were close to 0. The engines gradually exchanged pieces and pawns, on move 58 only QRB vs QRB remained, white had 2 pawns and black had 1. The engines mostly shuffled and gave checks, the game ended in a 50-move draw. In game 24 there were again no exchanges. The pawns in the center and the queen side were locked, Stockfish's eval gradually increased until it was over 1.5 but its plan was not clear. On move 37 the first pawn was taken, AllieStein pushed a pawn to the 2nd rank while Stockfish gave a knight for pawns and opened the king side, evals dropped to 0. AllieStein traded RB for Q, its king was exposed and the game ended in a check repetition.

In game 25 AllieStein kept its king uncastled, its eval slowly climbed over 1 while Stockfish's eval dropped to 0. The engines opened the king side and the black king was exposed, after many exchanges only QR vs QR remained with AllieStein a pawn up. The white king was also vulnerable and Stockfish started giving checks. Eventually the engines exchanged queens and the game was adjudicated.

Game 26 started similarly, Stockfish kept its king uncastled and pushed pawns on the king side. On move 20 AllieStein captured a knight after thinking less than a second, this opened the h file and Stockfish's eval jumped over 2.

The king side opened and the black king was exposed. AllieStein continued to follow its PV, it totally missed Stockfish's move 25, seeing the mate threat too late.

Stockfish captured the black queen and the game ended in mate on the board a few moves later. A game pair win for Stockfish.

AllieStein's eval started over 1 in game 27 and slowly increased. Stockfish opened a file in the center, most pieces stayed on the board and neither engine seemed ready to attack. The main difference between the engines was that AllieStein had a bishop pair and Stockfish had a knight pair.

The engines shuffled for a while and exchanged all rooks through the open file. AllieStein's eval jumped over 3, after exchanging queens the game reached a BB vs NN position. Stockfish continued to be calm with an eval below 1.

Stockfish's eval started to increase. It allowed AllieStein to capture a pawn on the king side and in return trapped a bishop in the corner. AllieStein's eval shot up and after arranging its pieces it exchanged the trapped bishop with a black knight.

The white king advanced and Stockfish couldn't protect the pawns on both sides. AllieStein captured a second pawn and the game was adjudicated a few moves later.

In game 28 evals started below 1 and gradually came down. Both central files opened, this time AllieStein kept one bishop. The engines used the open files to exchange a pair of rooks and queens as well. The engines continued to exchange pieces until only B vs N remained. AllieStein's eval turned negative but it had no real advantage. The game ended in a 50-move draw. AllieStein comes right back with a game pair win.

Games 29-30 started with a 20-ply book in the QGD opening, Rubinstein variation, with the kings castled in opposite directions. In game 29 there was a long series of exchanges and most pieces were gone. By move 28 only Q vs QB remained, white 3 pawns up for the bishop. AllieStein pushed pawns forward, it captured the bishop and allowed Stockfish to draw with check repetition. In game 30 AllieStein gave a pawn and opened the queen side, the pieces stayed on the board longer. AllieStein regained the pawn and the engines exchanged pieces until reaching a QRN va QRN position, evals coming down to 0. The black king was exposed and Stockfish gave checks, the game should have been stopped twice by the draw rule but the engines played on. The game ended with a check repetition draw.