Also an Improv game in which one actor sits in a chair and is prohibited from moving. All other actors take turns, One at a time, acting out scenes that have some significance in the chair'd actor's life, in a random chronological order. By the end of a (sucessful) game, a charicter with traits shaped by the events of his/her life has been developed.
The chair'd actor gives some feedback, but its mostly the other guys that form the meat of the game.
A non-chair'd actor would come up and say something like "Oh my god Billy, her leg is bleeding and you can see the bone!! AHHHH!", thus taking the role of a childhood friend and establishing circumstances.
It is now established that the chair'd actor's name is Billy, and a traumatic event (some chick's leg being mauled in from of him) took place when he was young
At this point another actor may come up to the stage and flash forward several years and take the role of the chair'd actor's mother with a FuXoRed leg.
(It could be his teacher, a classmate, his pet iguana, whatever.)
She might say something like "IT'S YOUR FAULT I HAVE A CHRONICLY MESSED UP LEG YOU HORRIBLE SON!!", which would then (possibly) leave an emotional scar that could be exploited by a later actor, and so on.
At the end of the game, Billy is a charicter if not with depth, then at least one with a mother with a fucked up leg.