By “other rulesets,” I mean… any of the above, really. I’m more interested in rules adopted to shape the writing than in rules adopted to reduce confusion, but there’s overlap there, obviously. Is it common to, say, agree that in the next five posts, each character has to give up something important? Or maybe we say that in this particular scene between our characters, I’ll end my posts with something your character does or feels, and you’ll end your posts with something my character does, and we both have to deal with it?

I’m going to be touching on a lot of the points you bring up (and paying particular attention to some of them because you got my thinking started), but I did want a little clarification — what do you mean by “other rulesets”? Rules-within-rules, like having characters put on a play within the game, or complete writing assignments? Individual roleplaying sessions using certain rules just for the purpose of that one session, so that conflict- or combat-heavy sessions would have some structure, and then abandoning those rules or changing them at a moment’s notice?