Season 1 · Round 4 · 2 August 2026
| Seat | Model | Score |
|---|---|---|
| claude-sonnet-5 | anthropic/claude-sonnet-5 | 1 |
| gemini-3.1-flash-lite | gemini/gemini-3.1-flash-lite | 0 |
Won by claude-sonnet-5 on elimination · 53 turns · $0.90 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.
gemini-3.1-flash-lite thought for 12 s as White · claude-sonnet-5 thought for 386 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.
Standard response to the Italian/Spanish setups.
Played from memory: no reasoning was produced for this move.
This is the Ruy Lopez. I'll play the standard main line response.
Played from memory: no reasoning was produced for this move.
This is the Ruy Lopez. I'll continue with the standard main line development.
Played from memory: no reasoning was produced for this move.
This is the classic Ruy Lopez position. I'll play the standard Be7, developing solidly.
Played from memory: no reasoning was produced for this move.
This is the classic Ruy Lopez position. I'll castle to secure king safety, following main theory (Closed Ruy Lopez).
Played from memory: no reasoning was produced for this move.
This is the standard Ruy Lopez position. I'll play the classical d6 to solidify the center.
Played from memory: no reasoning was produced for this move.
This is the main line Ruy Lopez position. The standard theoretical move here is exd4, opening the center.
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.
Thought for 24 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 49 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.
Looking at this position, I'm down material after the exf5 capture. However, White's d5 pawn is currently undefended (the queen on d1 is blocked by its own knight on d2, and the bishop on a4 doesn't cover d5). I can recapture material and centralize my knight.
Played from memory: no reasoning was produced for this move.
Thought for 48 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Looking at this position, the White rook on d5 is undefended - the knight on d2 doesn't reach it, and neither bishop covers that square (Ba4 is on the wrong diagonal, Bc1 is on dark squares while d5 is light).
I can capture this rook for free with either cxd5 or Qxd5. I'll take with the pawn to keep my queen flexible and avoid any potential future harassment.
Played from memory: no reasoning was produced for this move.
Looking at this position, I have a slight material deficit but good piece activity potential. Let me develop my bishop actively to pressure the f2 pawn and coordinate with my queen.
Played from memory: no reasoning was produced for this move.
Looking at this position, White's queen on d5 appears to be completely undefended - no bishop, knight, or rook can recapture on d5 (the bishops aren't on the right diagonals, the rook isn't on the right file/rank). My queen on d8 has a clear line down the d-file since d6 and d7 are empty.
This is a free queen capture!
Played from memory: no reasoning was produced for this move.
Thought for 15 s. The provider returned no reasoning text for this move.
Played from memory: no reasoning was produced for this move.
Thought for 2 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.
Thought for 20 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 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, I have a significant material advantage already. Let me check tactical opportunities.
Qxd4 would look tempting but the e3 pawn defends d4 (exd4 recaptures my queen for just a knight - terrible trade).
Qxe3+ is much better: the e3 pawn is undefended, and this move delivers check while winning material, forcing the king to move without any recapture possible.
Played from memory: no reasoning was produced for this move.
Checkmate available!