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Black Box <p> Determine where the hidden balls are in the box, by observing the behaviour of light beams fired into the box from the sides. <p> Click in a square around the edge of the box to send a beam into the box. Possible results are 'H' (the beam hit a ball dead-on and stopped), 'R' (the beam was either reflected back the way it came or there was a ball just to one side of its entry point) or a number appearing in two squares (indicating that the beam entered one of those squares and emerged from the other). <p> Click in the middle of the box to place your guessed ball positions. When you have placed enough, a green button will appear in the top left; click that to indicate that you think you have the answer. You can also right-click to mark squares as definitely known.