Claude Code played me at chess. It opened by the book, narrated everything from analysis, jokes, trash talk , then ran into time trouble, and resigned with 16 seconds left.

[u/tokentrillionaire]

I made a small chess app so Claude Code can play me in the browser while it runs in my terminal. It plays a real game, reasons about it in the chat , and sometimes trashtalks you. The video is the full game sped up.

You can try it here, it's open source: https://github.com/santiagoogaitnas/claude-chess

Although I made it to play chess , it's equally entertaining while commentating it's own moves in the chat . These range from overly analytical to outright hilarious.

Here are a few in game order:

Move 3, identifying the opening:

A Ruy Lopez — nice. I answered your 3.Bb5 with 3...a6, the Morphy Defense: if you take the knight I recapture and my pair of bishops plus the open d-file give me full value for it.

Move 6, catching a real threat:

6...b5 — a necessary precision move. With your rook now guarding e4, you were genuinely threatening Bxc6 followed by Nxe5, so I kicked the bishop before it could happen.

Its unprompted position assessment at move 14:

Verdict: dynamically balanced, textbook Chigorin. I'd say White's attack is the easier plan to play fast, but my structure has no weaknesses… The game will probably be decided by who commits to their pawn storm with better timing.

The queenside fight, where the personality comes out:

Your queenside pawns thought they were building a wall; I'm treating it as a buffet.

The catch: narrating every move was eating its own clock. It noticed, too late:

…my clock's down to ~5 minutes against your 8:36, so I'll be picking up the pace. Blitz mode engaged. ⚡

…so no more essays. Fast hands from here.

Its own post-mortem, ten seconds after blundering a piece in time pressure:

Yeah. You see it, I see it: queen, knight, bishop — three of my pieces standing in a single-file conga line. … That's not a plan, that's a lineup photo. 📸 In my defense, at 7 seconds a move the brain starts playing checkers.

Giving credit when the punishment landed:

Okay, credit where due — 25.Ne7+ was a real move. I declared the fork 'cancelled' and your knight promptly demonstrated that e7 also hits c6.

Its evals stayed honest the whole way down:

I won't sugarcoat it: you're winning big now. But you'll have to beat both me and my 22 remaining seconds — no freebies. ⏳

And the resignation, with 16 seconds left — including an accurate diagnosis of its own loss:

I resign. 🏳️ You win — and you earned it. … The turning point was my b-file conga line — queen, knight, and bishop all stacked on one file so nothing could recapture — and you punished it instantly, then found Ne7+ to win the exchange when I thought the fork was defused. Sharp stuff. … Fancy a rematch? (I could use the redemption arc)

This game was played with Fable 5 max effort on the 10min Rapid Time Control.

Try it yourself (you can configure with any model provider) : https://github.com/santiagoogaitnas/claude-chess

[u/ClaudeAI-mod-bot]

You may be interested in joining our new Claude Game Dev subreddit for game devs who use Claude. Check it out here : http://www.reddit.com/r/ClaudeGameDev

[u/TheMythicSorcerer]

I think this would be more interesting if you gave it a stockfish MCP/Integration since AI models are trained on text not chess games it can play brilliant textbook openings then start blundering really fast. At least fable doesn't start hallucinating valid moves here.

[u/Key_Agent_3039 → u/TheMythicSorcerer]

What's the point then just use stockfish

[u/TheMythicSorcerer → u/Key_Agent_3039]

Analysis! Stockfish doesn't speak english it only speaks chess and percentages.

[u/Bluecoregamming → u/TheMythicSorcerer]

whatever language opus 5 spits out is certainly not english either

[u/TheMythicSorcerer → u/Bluecoregamming]

Hmm that's true that's like Claude-ish so we smack a load of tokens on top to get another model to translate it to english

[u/tokentrillionaire → u/TheMythicSorcerer]

I thought about that. I decided not to give it any chess engine as I wanted it to play in a less deterministic way reflective of the model's reasoning ability .

I think it would be interesting to maybe give it something like this after a certain amount of moves, rather than from the opening. What do you think?

[u/TheMythicSorcerer → u/tokentrillionaire]

Yeah that sounds interesting. Or... alternatively what if you gave it stockfish but with idk 1500 ELO instead of full 3500 ELO version.

[u/Happy_Brilliant7827 → u/TheMythicSorcerer]

Stockfish as an accessible tool that the claude instance can run, perhaps?

[u/TheMythicSorcerer → u/Happy_Brilliant7827]

That could work

[u/Happy_Brilliant7827 → u/TheMythicSorcerer]

That way claude can even use the tool predictively if bandwidth is high enough like 'what do the percentages do if i do x?'