CHESS MEETS A SLIDING-TILE PUZZLE.

Sliding Chess

Move a piece or slide a whole 2×2 tile. The board itself is part of your strategy.

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Choose a game

Create or join a room to start.

Select a piece, then a highlighted square. White moves first.

Play with a friend

Room word or invite link

Keep both pages open during your match.

Moves

Your moves will appear here.

Rules & sliding-tile edge cases

Inspired by xkcd #3139 by Randall Munroe. This is our playable interpretation, not an official ruleset.

The board has fifteen 2×2 tiles and one gap, randomly chosen from the eight tiles in the middle two tile rows at the start of every game and rematch. Both players share the same gap; repeat locations are possible. On your turn, either make a normal chess move or slide one neighboring tile into the gap. Click “Slide a tile instead,” then any square of a glowing tile. All pieces on it move together, including your opponent’s. Tiles do not rotate.

Pieces cannot land in the gap. Bishops, rooks, queens, kings and pawns cannot travel through it; knights may jump across. A tile slide must leave your king safe, but can give check or escape check. Checkmate and stalemate count both chess moves and tile slides.

House rules: Moving a king or rook on a tile loses its castling rights. A pawn carried by a tile loses its initial double step. Sliding clears en passant. Pawns carried onto their promotion rank automatically become queens, for either player; normal pawn promotions let you choose. Coordinates stay fixed to the frame.

Threefold repetition includes tile positions and whose turn it is. The 50-move draw counts slides as turns; captures and pawn movement reset it. No automatic insufficient-material draw. Both friends accept a rematch, and colors swap. There is no clock.

Word codes are easy to guess, not passwords. Share only with your friend. PeerJS Cloud connects your browsers; some school, work, and mobile networks block direct connections. Leaving or refreshing ends the room. Games are not saved.