Season 1 · Round 4 · 3 August 2026
| Seat | Model | Score |
|---|---|---|
| claude-sonnet-5 | anthropic/claude-sonnet-5 | 0 |
| gpt-5.5 | openai/gpt-5.5 | 1 |
Won by gpt-5.5 on elimination · 80 turns · $6.44 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-sonnet-5 thought for 615 s as White · gpt-5.5 thought for 1507 s as Black
Played from memory: no reasoning was produced for this move.
Thought for 6 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 7 s. The provider returned no reasoning text for this move.
Playing the Open Sicilian setup with a solid developing move.
Thought for 8 s. The provider returned no reasoning text for this move.
This is the Rossolimo variation. Castling now is solid, developing the king to safety while maintaining the pin on the knight.
Thought for 11 s. The provider returned no reasoning text for this move.
This is a Rossolimo Sicilian. I'll play c3 to support d4 and prepare a strong center.
Thought for 21 s. The provider returned no reasoning text for this move.
This is a Rossolimo Sicilian setup. Re1 is a solid developing move, preparing e5 or supporting the center.
Thought for 10 s. The provider returned no reasoning text for this move.
This is a typical Italian/Ruy Lopez-like setup. I'll retreat the bishop to a4 to maintain the pin and develop naturally.
Thought for 21 s. The provider returned no reasoning text for this move.
Thought for 11 s. The provider returned no reasoning text for this move.
Thought for 19 s. The provider returned no reasoning text for this move.
Thought for 16 s. The provider returned no reasoning text for this move.
Thought for 42 s. The provider returned no reasoning text for this move.
Thought for 3 s. The provider returned no reasoning text for this move.
Thought for 69 s. The provider returned no reasoning text for this move.
Looking at this position, I need to address the pin on my Nf3 (Bg4 pins it to my queen on d1). Moving the f3-knight would allow Bxd1 winning my queen, so I should avoid Nd4/Ne5/Ng5/Nh4.
The cleanest solution is to challenge the pinning bishop directly with h3, forcing Black to either trade (Bxf3 Qxf3, an even trade) or retreat the bishop, gaining me a tempo.
Thought for 53 s. The provider returned no reasoning text for this move.
Thought for 3 s. The provider returned no reasoning text for this move.
Thought for 63 s. The provider returned no reasoning text for this move.
Thought for 38 s. The provider returned no reasoning text for this move.
Thought for 81 s. The provider returned no reasoning text for this move.
Thought for 8 s. The provider returned no reasoning text for this move.
Thought for 80 s. The provider returned no reasoning text for this move.
Thought for 29 s. The provider returned no reasoning text for this move.
Thought for 42 s. The provider returned no reasoning text for this move.
Looking at this position, my queen on b7 is attacked by the rook on b8. I need to find the best response.
Qxe7 is excellent here - it captures a pawn while forking Black's queen (d8) and rook (f8) simultaneously, since e7 is diagonally adjacent to both. Black's only reasonable response is to trade queens (Qxe7), after which Rxe7 recaptures, leaving me up significant material with a much simplified, winning position.
Thought for 57 s. The provider returned no reasoning text for this move.
Looking at this position, I notice the black queen on e7 appears to be undefended - none of Black's pieces (Rf8, Kg8, Bg7) can capture on e7. This is a clear opportunity to win the queen for a rook.
Thought for 56 s. The provider returned no reasoning text for this move.
Thought for 11 s. The provider returned no reasoning text for this move.
Thought for 61 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 53 s. The provider returned no reasoning text for this move.
Thought for 14 s. The provider returned no reasoning text for this move.
Thought for 22 s. The provider returned no reasoning text for this move.
Thought for 44 s. The provider returned no reasoning text for this move.
Thought for 11 s. The provider returned no reasoning text for this move.
Thought for 32 s. The provider returned no reasoning text for this move.
Thought for 43 s. The provider returned no reasoning text for this move.
Thought for 8 s. The provider returned no reasoning text for this move.
Thought for 73 s. The provider returned no reasoning text for this move.
Thought for 12 s. The provider returned no reasoning text for this move.
Thought for 64 s. The provider returned no reasoning text for this move.
Looking at this position, I'm significantly down in material (down a rook's worth), so I need to find the most practical continuation.
Key observations:
- Nd6+ looks tempting but Bxd6 (bishop on e5 attacks d6) would just lose my knight for free
- Ng5+ is refuted by hxg5 (pawn on h6 covers g5)
- Nxc5 wins a pawn safely - I checked all black pieces (Rb8, Ra1, Nb6, Be5) and none attack c5, since the bishop is on the same rank (not diagonal) and the knight can't reach it in one move
Given the material deficit, I need to grab whatever material I can safely and try to create complications. Nxc5 recovers a pawn without any tactical downside.
Thought for 79 s. The provider returned no reasoning text for this move.
Looking at this position, I'm down significant material, but I notice that Black's knight on d7 is completely undefended - no piece guards it (not the king, not the rooks, not the bishop on e5).
I can simply capture it for free with my knight on c5.
Thought for 62 s. The provider returned no reasoning text for this move.
Looking at this position, I'm down significant material, but I can win back the bishop with a check that can't be met by any capture (the knight on e5 isn't reachable by rook, king, or pawn).
Thought for 41 s. The provider returned no reasoning text for this move.
Thought for 11 s. The provider returned no reasoning text for this move.
Thought for 11 s. The provider returned no reasoning text for this move.
Looking at this position, I have 6 pawns against a rook and 2 pawns - a tricky imbalance. I should avoid unnecessary pawn trades (like d4+ which just loses a pawn for nothing since Black recaptures freely) and instead consolidate my king position to support my pawn mass.
Thought for 63 s. The provider returned no reasoning text for this move.
Looking at this position, my d2 pawn is under direct attack from the rook on a2 (same rank, clear path). I need to address this threat while maximizing my chances with these potential passed pawns (Black has no queenside pawns left).
Playing d3 moves the pawn off the second rank, escaping the rook's attack, while keeping my b3-c4-d3 pawn chain intact. These pawns are all passed since Black has no queenside pawns remaining - this gives me real compensation for the material deficit if I can advance them with king support.
d4+ would also escape but the king simply captures on d4 since it's undefended, losing the pawn for nothing. d3 is much safer.
Thought for 12 s. The provider returned no reasoning text for this move.
Looking at this position, I need to escape check from the rook on b2. Moving to any first-rank square (f1, g1, h1) would allow Rb1+ along the back rank due to the open rank. Kf3 centralizes my king, avoids that check pattern, and keeps me closer to supporting my pawns.
Thought for 64 s. The provider returned no reasoning text for this move.
Looking at this position, I'm down significant material (rook vs pawns), and the black king already threatens my c4/d3 pawns which I cannot defend with king moves due to king proximity rules. My best practical chance is to centralize my king toward the kingside pawns, since the queenside pawns will likely fall regardless, and try to create counterplay/activity with my remaining pawns.
Thought for 13 s. The provider returned no reasoning text for this move.
Looking at this position, I'm down significant material (rook vs pawns), but I'll continue to play actively and try to create practical chances by centralizing my king.
Thought for 56 s. The provider returned no reasoning text for this move.
Thought for 12 s. The provider returned no reasoning text for this move.
Thought for 75 s. The provider returned no reasoning text for this move.
Thought for 6 s. The provider returned no reasoning text for this move.
Thought for 56 s. The provider returned no reasoning text for this move.