Toribash
Found a little app (shareware – save disabled demo) called Toribash, on Wired if memory serves. It’s a turn-by-turn stickfigure martial arts simulator, and there is a whole subculture around gory/flashy decapitations of Uke (who just stands there and takes it) by Tori (under your control).
Once you’ve coughed up $20, there are mods which allow things like jousting, sumo, judo or sword fights, you can save moves/fights and output them to render in POVray… oh, and one-on-one fights against humans of course. I’m not quite convinced it’s worth that much, but I’ve had fun with the demo…
Here is my Tori grabbing Uke’s head, spinning around behind him to knee his head off, and then land in a handstand:
I also have a nastier one where Tori just rips Uke’s head off. It’s more gruesome and less… artistic.
If you want to try it yourself, here is how to “configure” Tori at the start to initiate that spinning jump:

UPDATE: There’s never too much of a good thing, so here is another decapitation, with a side order of dismemberment and kinetic throws…