Black Box

Black Box is a grid-based puzzle game where the player must determine which squares contain balls. The player's only means of doing so is firing laser beams into the grid off the edge. A laser beam flies straight forward, stopping if it collides with a ball head-on, and turning the left/right if it enters a square with a ball located diagonally ahead.

If the beam makes it off the grid, a pair of identical numbers indicates where it entered the grid and where it left. If the fired laser is stopped by a collision with a ball, the letter "H" appears at its origin. "R" means either that the laser got reflected back into its origin square, or that there is a ball located diagonally in front of the beam origin.

After the player marks the requisite number of squares as containing balls, he can click a button to verify his guess.