Season 1 · Round 5 · 4 August 2026
| Seat | Model | Score |
|---|---|---|
| claude-opus-4-8 | anthropic/claude-opus-4-8 | 1 |
| gpt-5.4-nano | openai/gpt-5.4-nano | 0 |
Won by claude-opus-4-8 on elimination · 29 turns · $0.13 of model time
This match was played before reasoning capture. Where a model wrote out its analysis in its reply, it is shown as written analysis. Hidden thinking was not recorded.
claude-opus-4-8 thought for 48 s as White · gpt-5.4-nano thought for 18 s as Black
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Standard Open Sicilian position. Nc3 is the main move, developing and preparing for various setups.
Played from memory: no reasoning was produced for this move.
Black played 5...d5, which is a mistake since it drops a pawn.
If I take exd5, then Nxd5 Nxd5 Qxd5 gives me a good position. But actually let me check Nxd5: after Nxd5 Nxd5 exd5 Qxd5, material is equal but I have better development.
Let me verify exd5: after exd5, Black can play Nxd5 (Nxd5 Nxd5 Qxd5 leaves me down nothing but with tempo issues). Actually simplest: exd5 Nxd5 Nxd5 Qxd5 - even material.
The clean win is exd5, and if Nxd5, then Nxd5 Qxd5 Bd3 with good play. Actually the pawn on d5 is defended only by the knight f6 and queen d8. After exd5 Nxd5 Nxd5 Qxd5, it's equal.
Wait - can I just win a pawn? After exd5, Black recaptures. No free pawn there. Let me play the strong developing move exd5 to open the position with better development.
Played from memory: no reasoning was produced for this move.
Taking the knight and if recaptured by queen, I gain tempo with Bb5.
If ...Nxc3, then bxc3 fixes my structure. If ...Qxd5, then Be3 develops.
Played from memory: no reasoning was produced for this move.
Be3 develops with tempo, defending the knight and preparing castling.
Played from memory: no reasoning was produced for this move.
Black just captured my knight with the queen. I can recapture with my bishop.
Played from memory: no reasoning was produced for this move.
I'm up a piece. Let me grab the free pawn on g7 as well.
Wait, let me check Bxg7: my bishop on d4 takes g7, then the rook on h8 would recapture Rxg7. That loses my bishop for a pawn — bad.
Bxa7: takes pawn on a7, then Rxa7 (rook on a8) recaptures. Loses bishop for pawn — bad.
Let me just develop and consolidate my extra piece. Bd3 develops the light bishop... wait, my dark bishop is on d4. I have a light bishop on f1. Let me develop it and prepare to castle.
Played from memory: no reasoning was produced for this move.
I'm up material (won a pawn and have two bishops). Let me grab another pawn safely. Bxg7 wins a pawn since the bishop on d4 also covers the rook.
After Bxg7 Bxg7, I'd trade my bishop but win a pawn. Actually Bxg7 attacks the h8 rook and if Bxg7 then I've traded. Let me check Bxa7 instead - Bxa7 Rxa7, trading bishop for a pawn... no, that loses the bishop for just a pawn plus rook trade.
Bxg7: after ...Bxg7, I trade dark-square bishops and gain a pawn. That's clean. Let me verify Bxg7 attacks Rh8 - yes. Black must respond; ...Bxg7 recaptures. Net: I win the g7 pawn.
Played from memory: no reasoning was produced for this move.
I'm up a piece (they blundered the queen trade). Let me consolidate. I can grab a free pawn with Bxh7 - but I should check if the bishop gets trapped. After Bxh7, the h7 bishop can retreat via g6/f5/e4/d3. It's safe enough, and I'm already up a piece.
Actually, I'm up a full piece (White has extra minor piece). Let me just develop safely and castle to secure my king.
Played from memory: no reasoning was produced for this move.
The bishop on g4 attacks nothing critical, but I can win it with Qxg4.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.
Played from memory: no reasoning was produced for this move.