Normal chess, until it isn't. After any move the two of you can trade
colors — and the player who just moved gets to move again, now as the other side.
Start a game
or
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How swap chess works
Turn order never changes: white moves, then black, then white. What changes is who is holding each side.
After a move, a swap may fire. You and your opponent trade colors on the spot.
Because the side to move is now yours, you move again — and your opponent inherits the position you just built.
Checkmate is judged before the swap roll, so a mate you deliver always ends the game in your favor.
Everything else is ordinary chess: castling, en passant, promotion, stalemate, the fifty-move rule.