In this two-player game, players line up four turtles in a row and lay out ten black and ten white balls. The turtles are two-sided and have a different number of holes on each side, although always an odd number. On a turn, a player either takes a ball of any color, places it on an empty hole on a turtle, and moves that turtle one space forward in line (assuming it's not at the front) or moves one of his balls already on a turtle backward to a different turtle, leaving all turtles in the same locations. The game ends when all the holes are filled, and the winner is the player who has the most balls on the turtle at the head of the line.