This is GNILLEY, and by God, this game is a scream. Literally. Built by Glen Forrester of Australia, you play by screaming your foes into oblivion or shouting down obstacles in your path.
The video is of Forrester showing GNILLEY this weekend at Global Game Jam Sydney 2010. Looks like he screams "GO!" to get the thing started, and from there, well, see and hear for yourself. It's hilarious. His creation took the festival's Most Original award.
Pro tip: for the regular version, you might need to open your Windows sound mixer and set recording volume to maximum.
It's available for download (PC) from the Game Jam site.
GNILLEY [The Global Game Jam, thanks Brett]