Black Box is a puzzle game in which one player creates a puzzle by secretly choosing the positions of 4-5 marbles on a 8x8 grid. The other player tries to guess their positions by shooting 'rays' into the grid and seeing how they bounce around. The player requiring the fewest rays to solve a puzzle wins.
A replacement for the pattern / score card if your original, like mine, is lost to the ages. Print it two-up and double sided to make a nice booklet of puzzles and results. Or scale it down a tad and laminate it if you prefer a reusable card.