Click on orbs arranged in a grid to make them all glow. Clicking on an orb changes its state from unlit to lit or lit to unlit along with the neighboring orbs. Turn on all the orbs to pass a level with as few moves as you can.
There are 9 levels, each with more orbs than the previous one. Two difficulty modes. In the easy mode, all orbs are unlit in the beginning and in the hard mode, some orbs are already lit to make things difficult for the player.