Sym is a black/white puzzle platform where you can switch between solid and hollow tiles. Some of these tiles behave as logic gates and change color depending on its neighbors. Also there is a level editor, and you can load online your levels and connect them with levels created by other user. Well, it's easier to see than to explain, so here's a trailer:
Help us to get on Steam, if you already own the game on Desura we have a free key for you!
Good luck! I hope you get on Steam soon