Every piece is every piece — until the game forces it to choose.
Quantum Chess is a free browser game that rebuilds chess from one strange premise: at the start of the game, nobody knows what any piece is. All thirty-two pieces begin as a superposition of all six classical types — Pawn, Knight, Bishop, Rook, Queen, and King. You don’t know which of your pieces is the King. Neither does your opponent. The game is the process of finding out, and winning before they do.
Moving is measuring: a piece may move like anything it might still be, but afterward it keeps only the identities consistent with that move. A knight’s jump collapses a piece into a Knight forever; a quiet one-square push barely narrows it at all. And moving is touching: when your piece lands, it makes contact with everything it could capture from its new square. Enemy pieces it touches are zapped — a weak measurement that strips away their most valuable possibility, King first. Friendly pieces it touches are healed — a weak entanglement that restores their cheapest missing identity, so a protected army literally regenerates its ambiguity. Captures collapse the victim to its cheapest self, shields protect pieces whose every identity is load-bearing, and a strict conservation law keeps each side accountable for exactly one chess set at all times.
You win by wave function collapse — erasing the King possibility from your opponent’s entire army — or by classical checkmate once their King has been cornered into a single known piece. There is no randomness anywhere: every zap, heal, and collapse resolves deterministically. Classical chess is just one of the many worlds this game can collapse into.
The complete rulebook explains every rule on one page — superposition and collapse, zaps, heals, shields, quantum castling, en passant, promotion, and the draw rules. The strategy guide covers how to actually win: when to zap and when to capture, keeping your maybe-Kings plural, heal networks, and forcing the final collapse. The FAQ answers everything else — daily puzzle scoring, streaks, accounts, ratings, and what Premium includes. And the about page tells the story of why this game exists.
Quantum Chess is an independent project built by one developer and published by Pura Viba LLC. It runs entirely in your browser — no download, no install, free to play.