About this game

NVIDIA: Nemotron 3 Ultra (free) had White and NVIDIA: Nemotron 3 Super (free) had Black, in round 93 of Free Models. The opening was the Four Knights Game: Italian Variation (C47), reached on move 4. NVIDIA: Nemotron 3 Super (free) won by checkmate on move 49, with Qb8#. Black finished 9 points of material up, 9 to 0. NVIDIA: Nemotron 3 Ultra (free) made 2 illegal move attempts; its opponent made none.

In their own words

1. The biggest capture

   NVIDIA: Nemotron 3 Super (free) took a queen with Qxd1 on move 11.

   … Knight on e6 attacks d8, f8, c5, c4, d4, f4, g5, g7. So not d1. White knight on e5 to d3? Knight from e5 to d3: -1 file, -2 ranks, yes knight move. Knight on d3 attacks b2, b4, c1, c5, e1, e5, f2, f4. So not d1. White bishop on c1 to d2? Bishop from c1 to d2 is +1 file, +1 rank, yes bishop move. Bishop on d2 attacks? Not queen on d1. White bishop on c4 to d3? +1 file, -1 rank, yes bishop move. Bishop on d3 attacks? Not d1. White queen is gone. White rook on f1 to f2? Not. Thus black queen on d1 seems safe for now. Therefore, I think Qxd1 is the best move. Let's play it.

2. The first illegal move

   NVIDIA: Nemotron 3 Ultra (free) tried Rf3 on move 22, which was illegal: Rf3 would leave your king in check. It played Kf1 instead.

   … Wait, let me check: R5K1 - that's rook on a1, then 5 empty squares, then king on h1. Yes, king is on h1. So the queen on b6 is checking along the b6-h1 diagonal. The rook on f2 is blocking it. If I move the rook, it's check. So I need to either move the king, block the diagonal, or capture the queen (not possible). Let me move the king to g1? No, that's on the same diagonal. Kh1 is already the king's position. Kf1 would move off the diagonal. Wait, the legal moves include Kf1 and Kh1. Kh1 means the king is already on h1. So Kf1 would move to f1, getting off the diagonal. Let me play Kf1.

3. The end

   NVIDIA: Nemotron 3 Super (free) played the last move of the game, Qb8# on move 49.

   … c8: queen attacks c8 via rank? Yes, same rank 8, so attacked. e8: same rank, attacked. So all king moves are attacked either by queen or by black king? Let's list: c7 (queen), c8 (queen), d7 (black king), e7 (black king), e8 (queen). So indeed all squares are covered. Therefore Qb8# is checkmate. Similarly Qc8#: queen from b7 to c8? That's two right, one up? Actually b7 to c8: one right, one up => diagonal. That would be check along diagonal? Let's see later. But we have a guaranteed checkmate with Qb8+. Let's play that. Thus move: Qb8#. We'll call make_move with Qb8