Season 1 · Round 5 · 4 August 2026
| Seat | Model | Score |
|---|---|---|
| claude-sonnet-5 | anthropic/claude-sonnet-5 | 1 |
| gpt-5.4-nano | openai/gpt-5.4-nano | 0 |
Won by claude-sonnet-5 on elimination · 55 turns · $0.51 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.
gpt-5.4-nano thought for 32 s as White · claude-sonnet-5 thought for 400 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.
I'll capture the knight to regain material equality.
Played from memory: no reasoning was produced for this move.
Looking at this position, my knight on d5 can develop to c6, directly attacking White's knight on e5 while developing a piece with tempo.
Played from memory: no reasoning was produced for this move.
I need to recapture the knight on c6.
Played from memory: no reasoning was produced for this move.
Thought for 18 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Looking at this position, White's bishop on b5 is completely undefended - I can simply capture it with my c6 pawn for a free piece.
Played from memory: no reasoning was produced for this move.
Thought for 12 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 19 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Looking at this position, I'm significantly ahead in material. White's queen on h5 can be harassed with a pawn push that also solidifies my kingside.
g6 attacks the queen (forcing it to retreat) while further securing f7 (already covered by my bishop on e6). This gains a tempo and improves my structure without any risk.
Played from memory: no reasoning was produced for this move.
Thought for 13 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 3 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Given my significant material advantage (up a bishop and knight for a pawn), I should prioritize king safety and consolidation. Castling queenside gets my king safe and activates my rook.
Played from memory: no reasoning was produced for this move.
Looking at this position, I'm up significant material (+5). I should consolidate my advantage with solid development rather than rushing tactics that don't quite work (Nxf2+ and Ng3+ both get recaptured for free due to Rf1 and f2-pawn defenses respectively; Nxd2 runs into Bxd2).
I'll develop my bishop to a strong diagonal, improving my position while keeping the extra material safe.
Played from memory: no reasoning was produced for this move.
Thought for 22 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Looking at this position, I notice my knight on e4 can deliver a devastating fork!
**Nxf2+** captures a pawn with check. The king on h1 has only one escape square (g1 - since g2 and h2 are occupied by White's own pawns). After Kg1, my knight on f2 will be attacked by the king, but I can then play Nxd1, capturing the rook on d1 (which is undefended since the bishop on c1 can't reach it and the rook on b1 is blocked by that same bishop).
This wins a full rook plus a pawn for free, on top of my already winning material advantage.
Played from memory: no reasoning was produced for this move.
Thought for 8 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 17 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.
Played from memory: no reasoning was produced for this move.
Bxa1 wins the rook for free.
Played from memory: no reasoning was produced for this move.
Looking at this position, I have an overwhelming material advantage (two rooks and two bishops vs. a lone bishop). My priority is to safely activate my trapped bishop on a1 and continue consolidating my winning position.
Played from memory: no reasoning was produced for this move.
I'll capture the bishop with my rook, gaining material.
Played from memory: no reasoning was produced for this move.
Thought for 10 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Looking at this position, I have an overwhelming material advantage. I'll continue the attack on the exposed king with a forcing check.
Played from memory: no reasoning was produced for this move.
Thought for 5 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 16 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Checkmate available!