Chess
Full legal chess in your browser — castling, en passant, promotion, checkmate — against the computer or a friend.
Click a piece to see its legal moves · Click a highlighted square to move · Arrow keys + Space/Enter · Z to undo
How to Play Chess in 3 Steps
Select a piece
Click any of your pieces to see every strictly legal destination — moves that would leave your king in check are filtered out automatically.
Play special moves naturally
Castle by moving your king two squares toward the rook; capture en passant by moving your pawn diagonally into the passed square; promote a pawn on the 8th rank by choosing Queen, Rook, Bishop or Knight.
Read the move list & undo
Every move is recorded in algebraic notation beside the board. Press Undo (Z) to take back a full turn at any time.
Controls & rules
| Action | Keyboard | Mouse / Touch |
|---|---|---|
| Select & move | ← → ↑ ↓ then Space / Enter | Click / tap piece, then destination |
| Castle | Select King → move 2 squares left or right | Click King, then g1/c1 (or g8/c8) |
| Promote pawn | Click ♕ ♖ ♗ ♘ in the promotion bar | Tap desired piece |
| Undo turn | Z | Tap Undo |
Chess — Frequently Asked Questions
Are all official chess rules enforced?
Yes: king safety (no moving into or leaving yourself in check), kingside and queenside castling (blocked if the king is in check, passes through check, or either piece has moved), en passant, pawn promotion to Q/R/B/N, checkmate, stalemate and the 50-move / threefold-repetition draw rules.
How does the computer evaluate positions?
It uses material balance plus piece-square tables (encouraging centre control, knight outposts, king safety and advanced pawns) searched with alpha–beta pruning and capture ordering — all in ~150 lines of JavaScript with no external engine.
Can I play as Black?
Open Game options and set “Play as” to Black; the board flips automatically so your pieces sit at the bottom.
Why can’t I castle right now?
Castling is legal only when neither the king nor the chosen rook has moved, every square between them is empty, the king is not currently in check, and the king does not pass through or land on an attacked square.
Is anything uploaded or tracked while I play?
No. The game runs entirely in your browser tab. Your best score or win tally is saved only in your browser’s localStorage and cleared when you press Reset.