You play the first moves of a game against a chess engine. The moment you make a mistake, or miss a chance your opponent gave you, the run stops.
Play. Tap a piece, then the square it goes to (or drag it). Known opening moves are accepted at once, and the opening’s name appears as you go.
Get stopped. You see the move you played, the better move, the engine’s score for both, and the line that follows each. Tap the moves to play them out on the board.
Go again. Start a new run, or take the move back and try the position again. A line you slipped in comes back in later runs, and stays on your list until you get it right.
Pick your opponent in Settings: a Master never slips, so you have to play accurately; a Club player or a Beginner makes mistakes, and you are expected to notice and punish them. Reach the last move of the run without a stop and it counts as clean. Your progress stays in this browser.