Three-check

Three-check keeps the normal rules for piece movement, check, and checkmate, but adds another main way to win: be the first player to check the opposing king three times during the game. A check means that after a legal move, the king is attacked and must respond as in standard chess.

Each move that leaves the opposing king in check adds only one check to the count. If a single move creates a double check, meaning two pieces attack the king at once, it still counts as one check because only one move placed the king under attack.

The third check wins immediately as long as the move is legal, even if the opposing king would otherwise have an escape on the next turn. Ordinary checkmate also remains a valid way to win, so a player does not need to reach three checks if checkmate comes first.

Unlike a variant such as King of the Hill, the extra objective here depends on how many times you attack the opposing king, not on moving your own king to a special square.