Toribash is essentially a turn-based 3D fighting game with no predefined punches, kicks, or other moves. You create them by manipulating individual joints. You can also grab enemies and throw dismembered body parts.
Different gamemodes include Sumo, Kickboxing, Joust, and Swords.
The game is entirely free and features singleplayer and multiplayer combat. Of course, if you can't make your fighter do anything other than spaz out, there's a crapton of documented moves here.
Toribash can be downloaded here.