Chess with a fourth direction.
A demo game is playing. Drag the tesseract to rotate it, scroll to zoom, or tap a piece on the flat boards to take over.
Four boards make one tesseract. A rook slides from one board to the same square on the next; your king can be in check from a piece in the other cube. Play people or the computer, free, no account needed.
Play online
Bullet, blitz, rapid, classical and daily games. Rated with Glicko-2, or casual.
Play the computer
Four levels, from a pawn that blunders to a queen that searches four plies deep.
Puzzles
Mate in one and two across the boards, rated so they keep pace with you. Plus Puzzle Rush.
Tournaments
Hourly arenas. Join late, get paired the moment you are free, streak for double points.
Learn
From 3D to 4D in four steps, with every piece's reach lit up on a live board.
Analysis board
Set up any position, try both sides, and ask the engine what it thinks.
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How 4D chess works
Every square has four coordinates: file (X), rank (Y), which board column (Z) and which board row (W). The four 4×4 boards on screen are one 4×4×2×2 hypercube. A rook changes exactly one coordinate, a bishop exactly two by the same amount, a queen any set, the king one step on any combination, and a knight jumps two on X or Y and one on another axis.
That is the whole trick. Moving a rook from a1 on the bottom-left board to a1 on the top-left board is a straight move along W. Two lines that cross in the 3D projection do not share a square. Checkmate wins; there is no castling, en passant or double pawn push.
Learn the rules