Select from 3 levels of difficulty for the computer player.
Players take turns and select a marble to drop down the board.
When a marble reaches an arrow box, it moves in the direction of the arrow, and the arrow changes direction. Gray boxes stop marbles until all 40 have been dropped. Then these boxes disappear and any marbles on top of them continue down the board for more points. Get as many marbles off the board as possible, and place the remainder carefully - try to block opponents by flipping their arrow boxes.