Chess on a twisted strip with one side and one edge. Drag to turn it, tap a piece to move.
How to play
The board is a Möbius strip 5 files wide (a to e) with squares on both faces: 12 squares go round the strip, and because of the half twist one face carries on into the other, giving one loop of 24 ranks. Rank 13 is the back of rank 1, rank 14 the back of rank 2, and so on. A piece can never jump through the sheet: to reach the other face it must travel all the way along the strip. Moving across the strip stops at its edges.
White starts on ranks 3, 4 and 5, Black on ranks 15, 16 and 17, on the other face of the same spot. Each army has a row of pawns in front of its back rank and a second row behind it, which guards the back through the twist, so queens and rooks cannot attack from behind at the start.
Pawns step one square toward the enemy home rank the short way (front pawns straight ahead, back-row pawns the other way round through the twist), capture one square diagonally forward, never move two squares, and become a queen on the enemy home rank (rank 16 for White, rank 4 for Black). There is no castling or en passant. Checkmate wins; stalemate, threefold repetition, 50 moves without a capture or pawn move, and bare kings are draws.