Geist
That game was crazy fun, controlling things from a paint can to a soldier and having to jump from thing to thing worked wicked well, I had more fun with that than most (keyword most) FPS games out there (those included are KZ2 and Battlefield Bad Company 1 among others)
And there's one part of a game that people probably overlooked that I played so many times, the snow/sandboarding levels in the first Tak games were SO fun, I played them so much I lost count of how many times I did them. The game itself was wacky and pretty fun, but these 2 levels in particular were REALLY fun ^^