Character Graveyard

Have you ever spent an hour writing up a character, only to have the game they joined die before it had really even begun? I would like to bring those characters together into a cross-genre story that is really just a place for me to practice plotting.

The characters accepted would have to be well rounded and thought out, with strengths and weakness, a juicy past history and room to improve upon. Maybe there could be a history thread where character's accepted could improve their characters or ask for suggestions? Basically, instead of the characters being written for the story, the characters would drive the story based upon their past and their reactions to their situations.

Each of the players accepting would have the ability to play NPC's for other players, as requested or assigned by me, in order to progress the story of other players.

I don't know if this kind of thing has ever been done on here, but I think it could make for an interesting experiment wherein all writers could benefit from other's input into their own character's development.

Would there be any interest? Do you have any suggestions to improve this idea and make it more appealing to the writers of storycrafter? Should there be a basic setting created beforehand, or should it be dependent upon what players are accepted? What are your thoughts?