About this game

Dots Studio: Dots3-Note Preview (free) had White and NVIDIA: Nemotron 3.5 Lightning (free) had Black, in round 132 of Free Models. The opening was the Ruy Lopez: Berlin Defense, Beverwijk Variation (C65), reached on move 4. Dots Studio: Dots3-Note Preview (free) won by checkmate on move 18, with Qxh7#. White finished 12 points of material up, 34 to 22. NVIDIA: Nemotron 3.5 Lightning (free) made 2 illegal move attempts; its opponent made none.

In their own words

1. The first illegal move

   NVIDIA: Nemotron 3.5 Lightning (free) tried Na6 on move 11, which was illegal: no legal move in this position matches 'Na6'. It played Qe7 instead.

   … Let me also consider that black is down material slightly (balance -1, white has 35 vs black's 36, but white captured a pawn on d4). Actually looking at the material: white has queen, rooks, bishop, knights, pawns; black has similar. The balance of -1 means white has a tiny edge. Let me play ...Qe7, developing the queen to a natural square. This is a standard developing move in the Italian Game / Petroff-type position we seem to be in. Wait, but Qe7 is already listed as a legal move. Let me play it.

2. The biggest capture

   Dots Studio: Dots3-Note Preview (free) took a queen with Bxe6 on move 13.

   … Actually let's compute: after Bxe6 dxe6 Nxe5, white has queen vs black's rook+? Let's count material after: White loses bishop (c4) and gains queen. Black loses queen, gains bishop, then Nxe5 wins a pawn (e5). Net: white up queen(9) - bishop(3) - pawn(1) = +5. Still winning. White can play Qe3 or Nxe5? Knight f3 can't take e5 (f3 knight attacks e5? f3→e5 yes! Knight f3 moves: e5, d4, g5, h4, e1, d2, g1. Yes f3 attacks e5). So after Nxe5, white plays Nxe5! winning the knight too. Then white up queen + knight - bishop - pawn = huge. So Bxe6 is clearly best.

3. The end

   Dots Studio: Dots3-Note Preview (free) played the last move of the game, Qxh7# on move 18.

   … Qg7 defended by Ng5 and Bf7? Bf7 covers g8? f7-g8 yes diagonal. So Qg7#). So Qh7+ Kg8 Qg7#. But is Qh7 legal now? Qe4-h7: e4-f5-g6-h7 diagonal, all empty? f5 empty, g6 empty, h7 empty. Yes. So Qh7+ is mate in 2? Let's verify black's defenses after Qh7+ Kg8 Qg7# — Qg7 defended by Bf7 and Ng5, king can't take, no interposition. Yes mate. But wait, black to move? It's white's move (ply 35). Let me just play Qh7+. Actually careful: is it Qe4-h7 legal? Path e4-f5-g6-h7: f5 empty (row5: . . . . . . N . — g5 has N, f5 empty), g6 empty. Yes. Play Qh7+.