Box

OX is an implementation of the Black Box puzzle game, in which you probe the eponymous black box by sending beams of light into the sides of a grid. These beams can be absorbed, reflected, or pass through the box either in a straight line or after a number of deflections. From the behaviour of the beams, you must deduce the location of several atoms hidden inside the box.

The interface is clean, and the gameplay is quick. You can choose the number of atoms in the box; the default of five atoms is a reasonable challenge for beginners. My only gripe with this version is that there's very little hoopla (or messaging of any kind!) when you win. I was waiting for something to happen when I solved the puzzle, but all you get is a HOW MANY ATOMS? prompt which is actually an invitation to play another game.