Your objective is to either score as many points as possible by forming and then removing large clusters of a single color, or to simply try and clear the board.
All the pieces in a cluster must be touching by at least one side. Pieces connected by a corner are not considered touching.
Remove blocks from the game board by clicking on a cluster or two or more like-colored pieces. You get exponentially more points for removing large clusters. Your score is (n-2)^2 where n is the number of pieces in a cluster. The trick is to remove smaller clusters in an attempt to form large ones.
Press the Undo button to take a step back. You are only allowed to undo the most recent step. The game is over when no more clusters of two or more pieces exist. To start a new game, press the New Game button.