Black box is a square box that contains cells. Some of those cells can contain a ball but you cannot see them. You can emit ray into the black box from its sides. Rays interact with balls inside the black box according to several rules. You have to determine the location of all balls in the black box relying on the results of emitting of the rays. Following are the rules of the rays and balls interaction inside the black box: - Ray that doesn't come across with any ball will go straight through the box - Ray that hits a ball will be absorbed (it will not come outside the box) - Ray that goes one cell to the left or to the right of a ball will be deflected by 90 degrees out of the ball - Ray that goes between two balls placed at the distance of one cell from each other will be turned around - deflected by 180 degrees - Ray that goes into the black box on the left or on the right side of a ball that stands by the box's side will be turned around immediately - Two or more balls standing near each other could merge the rays' routes. This can cause additional difficulties in finding the correct location of the balls. There are more detailed rules description in the Help window inside the game. You can also read about this game in Wikipedia: http://en.wikipedia.org/wiki/Black_Box_(game)