chess-engine

A playable chess board where a small engine answers your moves.

What it does

• Full chess rules via chess.js: castling, en passant, promotion, draws.
• Drag and drop a piece; the engine replies as the other side.
• Minimax with alpha-beta pruning and a simple material evaluation.
• Checkmate is scored, so it prefers the shortest forced win.

Stack

React 19, TypeScript, chess.js, react-chessboard, Create React App, Jest.

Run it

npm install
npm start        # http://localhost:3000
npm test         # engine tests
npm run build    # production build

What was hard

The first version answered with random moves. A real answer meant separating evaluation from the search and making minimax undo every move it plays, or the position drifts between branches. The tests pin three things now: a legal move from the start, a mate in one, and capturing a hanging queen.