If you haven’t played Toribash yet, you’re missing out. This is a free-to-play, physics-based fighting simulator, and you can easily waste hours on end making up new ways to rip apart your opponent.
It features a free-play mode in which you direct the action, a vs. mode against a computer-controlled Uke, or test your skills against live opponents in Multiplayer. There are hundreds of mods, skins and rules to customize your game with as well. If you’re on Steam, give these guys an up-vote on Greenlight.