Cobalt - a game by Oxeye Game Studio in collaboration with Mojang and music by Anosou.

bought this a while back.. its a fun game. its still in development but you can buy the alpha version for real cheap

"Cobalt is an awesome platform game featuring several game modes in both same computer multiplayer and in singleplayer. Cobalt comes with a game editor where players can create their own maps and adventures. Cobalt is ALSO a platform game engine that can be used to create new modes or completely new games."

click--> http://playcobalt.com/