A 3x3 grid of tiles is manipulated by rotating 2x2 squares within it. The object is to arrange the tiles into a given pattern. Within the 3x3 grid, there are four 2x2 squares within it that you can rotate: the four tiles in the upper left, the four tiles in the upper right, the four tiles in the lower left, and the four tiles in the lower right. You can rotate these 2x2 squares either clockwise or counterclockwise.
You can choose one of several modes. The modes are given in order of difficulty, from easiest to hardest. Each has a different final pattern to achieve.
You can save your game by bookmarking the page in the game you want to come back to later. This works for all pages of the game except for the first (which has "newgame" in the URL), so if you want to bookmark a particular puzzle from the beginning, you have to make at least one move first.