Crossover is played on a 5x5 grid with 25 pieces with different colors on each side. Two markers are also required which move along two edges of the board - one is controlled by each player. On a turn a player moves their marker and then places a piece at the space the two markers are pointing at, if it is empty. If a player cannot move to point to an empty space they point to an occupied space and flip the piece there over, regardless of which side is currently showing. The winner is the first to get four pieces of their color in a contunuous orthogonal line.