Discovery
$0
- 10 free games
- Léon, Stockfish and every engine
- Unlimited analysis workshop
The chess coach you can talk to.
Léon explains your moves, answers your questions out loud and remembers your mistakes. Across the board, different minds await: explore their choices and preferences.
10 free games · no credit card needed
JEV · StrategistDecision engine · TypeSafe
Your turn
A coach by your side.
Why was my knight badly placed?
Léon
On the edge, your knight controlled fewer squares. Let’s find a more active square near the centre.
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He explains every move
Good move, inaccuracy, blunder: Léon explains what really happened, with an arrow showing the best move on the board.
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He answers spoken and written questions
Ask “what opening is this?” or “what are the threats?”. He answers out loud while you stay in the game.
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He remembers your mistakes
Recurring weaknesses become targeted exercises, game after game.
One board. Many minds.
Stockfish calculates. Then a decision engine chooses from the best moves, in its own style. Compare JEV, Decider, Qwen and MiniCPM on the same position, with probabilities to explore.
- JEVCloud · TypeSafeNf364 %
- dDeciderOn your device · 1.3 GBNc342 %
Qwen3On your device · 397 MBNf370 %
MiniCPM5On your device · 1.6 GBNf377 %- 3.5Qwen3.5On your device · 3 GBNc373 %
An illustration of model preferences, not live analysis. Percentages refer to the proposed moves, not the chances of winning. Explore their choices
Your device makes its move.
Stockfish and four AI models run in your browser. Your game history stays on your device. JEV and coaching features that use it connect to the cloud.
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Sign in with Google
One account for access and your subscription. Your saved games stay in this browser.
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Choose your opponent
Stockfish, JEV or a local model: adjust its strength from Beginner to Master.
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Play, listen, improve
Léon explains, answers and turns your mistakes into exercises.
Simple pricing.
Start for free. Upgrade to Premium whenever you like.
Premium
$4.99 / month
- Unlimited games
- All Discovery tools
- Cancel anytime
Prices in US dollars · Secure payments by Stripe.
Local models depend on your device’s capabilities. JEV calls remain capped per game.
Any questions?
Everything you need to know before your first game.
What is PolyMind Chess?
A conversational chess coach. Play in your browser while Léon explains your moves, answers your questions and remembers your mistakes to suggest exercises.
Do I need to install anything?
No app to install. Local models are downloaded and kept in your browser while its storage remains available. Compatibility depends on memory and browser support; larger models need a suitable computer.
What is a decision engine?
An AI model that chooses between specific options. Stockfish proposes moves, then the model evaluates them according to the selected mode and style. The scores show its preferences, without revealing its internal reasoning.
Are my games sent to a server?
Your game history and Léon’s memory are saved in your browser. Accounts and billing are managed online. JEV and coaching features that use JEV send the position or question to TypeSafe; local models compute on your device.
What level do I need to start?
None. Léon adapts to beginners and club players alike, and you can adjust your opponent’s strength from Beginner to Master.
How do I cancel Premium?
Open My account, then Manage subscription. Follow the steps in Stripe’s secure portal; your access stays active until the end of the paid period.
Your next game starts here.
Play for free