Battle Slugs is essentially a stylized version of the old Chinese game Go. You start with two different colors of playing pieces which jump around the board in different ways. Jump one space to produce a cloned slug or two spaces to move the slug you're controlling. When you land next to a piece of the opposite color, it changes color.
Those are basically the only rules, but like Go, the strategy gets complicated quickly. You want to try and claim space on the board (the one you're playing at least -- there are 25 different levels in the game), but you have to do so carefully, because overextending can make trouble quickly. The game's actually pretty hard -- I had trouble mastering even the first level consistently.
Battle Slugs