Hammerfight is a game where you control a flying coffee grinder with a giant hammer attached and smack other flying things into bits.
http://www.youtube.com/watch?v=SIr45zHb9c4&feature=relatedIt looks all nice and friendly and then it hits you in the face with a point blank siege bomb. Then you crawl away and play a few rounds of hammerball only to find the ball replaced with a giant electrocuting murder machine. Of course by then you're used to that stuff because you fought the first boss at night with an escort mission going on.
There's a branching storyline and plenty of modes, just make sure to set the mouse DPI to about half what it suggests. It's totally worth the money.