Complete a row of four stones in a vertical, horizontal or diagonal line. Each turn, place two stones on the board or remove an opponent's stone if your stones are on twin symbols. Polished river stones are used as the pieces. The wooden board, which is a 4x4 grid, also contains a drawer for holding the stones. Contains rules in English, French and Spanish. A hockey themed version named "BrainPucks", licensed by the NHL, also exists. Instead of using abstract symbols, players match hockey team logos