There was an amusing video doing the rounds a while ago that essentially showed Mario being a bit of a jerk with the titular gun from Portal.
Indie studio Stabyourself (charming) has decided to make an actual game out of this concept, called Mari0. The game supports co-operative play for four players, has a map editor, DLC, hats and runs on Windows, Macs and Linux-based systems.
Apparently it can be a bit tricky to get running, but it looks like a heck of a lot of fun.
