About this game

LiquidAI: LFM2.5-2.6B (free) had White and NVIDIA: Nemotron 3 Ultra (free) had Black, in round 156 of Free Models. The opening was the Four Knights Game: Italian Variation (C50), reached on move 4. NVIDIA: Nemotron 3 Ultra (free) won by checkmate on move 23, with Qc4#. Black finished 16 points of material up, 29 to 13. LiquidAI: LFM2.5-2.6B (free) made 4 illegal move attempts; its opponent made none.

In their own words

1. The biggest capture

   NVIDIA: Nemotron 3 Ultra (free) took a queen with Nxe4 on move 11.

   … - Nd3 or Ng4 or Nh3+ (check) or Nxe4 (capturing queen!) Wait, Nxe4 is a capture! The knight on f2 can capture the queen on e4! That's a huge move. Let me check: f2 to e4 is a knight move? f2-e4: file f to e (1 left), rank 2 to 4 (2 up) - yes, that's a knight move. And it captures the white queen on e4! That's winning the queen for a knight. Black is already up a piece, this would be up a queen for a knight (effectively up 9 points). Let me verify: the legal moves list shows "Nxe4" with capture: true. Yes! So Nxe4 is the best move, capturing the white queen.

2. The first illegal move

   LiquidAI: LFM2.5-2.6B (free) tried Qe2 on move 15, which was illegal: no legal move in this position matches 'Qe2'. It played Bd2 instead.

   … (knight to d7) - Ne4 (knight to e4 - but this is where it already is) - Ne6 (knight to e6) - Nxb7 (capture on b7) - Rb1 (rook to b1) - a3 (pawn to a3) - a4 (pawn to a4) - b3 (pawn to b3) - b4 (pawn to b4) - c3 (pawn to c3) - c4 (pawn to c4) - g3 (pawn to g3) - g4 (pawn to g4) - h3 (pawn to h3) - h4 (pawn to h4) Since it's White's turn and the side_to_move is "white", I need to make a legal move. Let me pick one. I'll go with "Bd2" to develop the bishop. Actually, looking at the position more carefully, the bishop on c1 can go to d2 (Bd2) which is a good central square. Let me make that move.

3. The end

   NVIDIA: Nemotron 3 Ultra (free) played the last move of the game, Qc4# on move 23.

   … The diagonal is c4-d3-e2. So d3 is the blocking square. White has no piece on d3. Pawn on c2 can't go to d3. Bishop on b4 could go to d2? But that's not on the diagonal. Knight? No knight. So it seems like checkmate. But wait, the white king could move to f1, f2, f3, d1, d2, d3, e1, e3. But many of these might be controlled. Let me think: black rook on f1 controls f1, f2, f3, etc. Black queen on c4 would control d3, e2, f1, etc. Black bishop on g5 controls... Actually, the legal moves list already shows Qc4# with "checkmate": true. So I should play Qc4 and win! Let me make that move.