Collect as many green boxes as possible before the timer reaches 20. When you touch the green box, you gain a point, you are returned to the starting place, and the green box randomly reappears somewhere else on the screen. You can also not touch the black box or you die. You can go off the screen, though, and you will have to in order to get to the green boxes (that is part of the fun of the game). When you go off the screen to the left, you appear on the right, and vice versa, and when you go off on the top, you appear on the bottom, and vice versa.

http://forums.qj.net/showthread.php?t=138792