Though it may not look like it, this board uses the standard chess pieces—but their identities are unknown to both players and the computer. Their roles are defined as the game progresses.
This is "Quantum Chess" because each piece starts in a superposition (a "superpiece"). Each superpiece could be several different pieces, and its moves must always match at least one of its possible identities. It’s as if it was always just one valid piece throughout.
Fortunately, the game tracks possibilities for you. Every superpiece starts as a wildcard (★). If it moves one square forward, it becomes ♚♛♜♟, since only those pieces can do that. From then on, it can't make Knight or Bishop moves.
If a superpiece is narrowed down to just a Queen ♛, none of your other pieces can be Queens. You only get one! A single move can affect multiple pieces this way—it's up to you to explore those interactions.
What about check? A player is in check only if every possible King is in check. The same goes for checkmate. Capturing a superpiece retroactively proves it wasn’t the King, which you can use to your advantage.