Question 1

What is Chester AI Chess?

Accepted Answer

Chester AI Chess is a free online chess game where you play against Chester, an AI coach with personality. Chester evaluates every move in real time, comments on your decisions, and adapts to your skill level using an Elo rating system.

Question 2

Is Chester AI Chess free to play?

Accepted Answer

Yes. The Free tier includes daily AI moves and chat coaching at no cost. Pro ($9.99/mo) and Premium ($19.99/mo) plans unlock higher daily limits and unlimited usage respectively.

Question 3

How does the Elo rating work in Chester?

Accepted Answer

Chester uses standard Elo with a K-factor of 32. Your rating goes up when you win and down when you lose, weighted by the engine difficulty you faced. Difficulty auto-adjusts: under 1000 Elo faces an easier engine, 1000–1399 a medium engine, and 1400+ the strongest setting.

Question 4

What engine powers Chester?

Accepted Answer

Chester runs a custom JavaScript chess engine with minimax, alpha-beta pruning, a transposition table, and an opening book. Coaching commentary and move analysis are generated by the Anthropic Claude API.

Question 5

Can I play Chester on mobile?

Accepted Answer

Yes. Chester AI Chess is a Progressive Web App (PWA), so you can install it on iOS and Android straight from the browser. Your games and settings sync across devices when signed in.

Question 6

How is Chester different from chess.com or Lichess?

Accepted Answer

Chester is focused on single-player practice with an AI coach that speaks in plain English. Instead of just an engine evaluation bar, Chester commentates each move with personality, explains the reasoning, and adapts difficulty to your rating. It is complementary to multiplayer sites, not a replacement.

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