I have no idea weather or not this has been suggested before, and I don't have time to check. >_>
Anyway, this is basically having a link on the top of the page when editing your storygames that goes to a page where it has a record of all the edits, what the person did, when, and where. Like on google docs. And if say, everything gets deleted on the story except the game itself, or a co-author deletes certain things and adds a bunch of other things you didn't want (though this would probably only happen because a extreme lack of communication, or misunderstanding), then you could go the the earlier revision page and restore what was deleted.