The game consists of 3-by-3 ,4-by-4 and 5-by-5 grid of lights; when the game starts, a set of these lights (random, or one of a set of stored puzzle patterns) are switched on.  Pressing one of the lights will toggle it, and the four lights adjacent to it, on and off. (Diagonal neighbors are not affected.)  The game provides a puzzle: given some initial configuration where some lights are on and some are off, the goal is to switch all the lights off, preferably in as few button presses as possible.