I recently found a side-scroller shooting game (Platypus) that used claymation for every object. I've never heard of using claymation in games before, but it's actually pretty cool.
You can read the creators story of the game here: http://www.squashysoftware.com/makingplatypus.php
Pretty sad, actually.
Anyway, I just thought that was interesting. It'd be really cool to see someone make a game like this with GE.