Proton

This game is missing an infobox. If you're familiar with this game, feel free to fill one in.

Proton is a puzzle game for one or two players by Looney Labs. It is similar to the 15 puzzle, in which you have to rearrange 15 squares in a 16 square grid.

Clark Rodeffer has created a Protonic Rubik's cube that allows you to play a similar game on a Rubik's cube.

For complete details, see the Proton page.