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CHESS

Chess

Complete legal chess, proved by perft against the published node counts: castling, en passant, promotion, the fifty-move rule, threefold repetition and insufficient material. Three bot levels are fixed node budgets rather than clocks, so the move you get is the move the test suite measured. Online play is server-authoritative — a modified client cannot move a piece it does not own. Chess960 is a settings toggle, because the castling rule here is already general enough for it.

👥 Local Two-Player Two players, one device. White sits at the bottom and moves first. Click or drag a piece; the dots show every legal square.
🤖 vs Computer Three levels, each a fixed node budget — so the move you get is the move the test suite measured, whatever else the machine is doing.
🌍 Online Versus Open a room, send the four-digit code. The server owns the board, so a tap that would leave your king in check is refused there — and the creator's variant and seed are locked for the room.
🧩 Mate Puzzles Six positions the engine PROVED are forced mates, one of them a Chess960 castling mate. A wrong move tells you the truth — how many of your legal moves actually win.
To move White
White 16
Black 16
Material even
Mode Local
Opponent —
Engine —
FEN & PGN

Mate Puzzles

Every position here has been through the engine's verifier: a forced mate within the stated plies against every reply, at least one legal move that does not mate, and no faster mate than the one claimed. A generator that cannot prove a position returns nothing rather than inventing a puzzle.

Settings

Game

Chess960 randomises the back rank, so castling needs the general rule — which is the only rule this engine has. The seed chooses the arrangement.

Display

Puzzles

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