I've seen a lot of gameplay which leverages handing around Kerbal Space Program saves like that, too. You can get up to all sorts of mad shenanigans that way.
I was thinking about some of my old, shit-canned designs, and it might be reasonable to break out one of the "resource allocation" games which I was tinkering around with as a way to play by post with people who don't necessarily have the ability to respond in a synchronous manner. The key mechanic was to recognize that each player only has so many Tokens to invest in the reality of a given statement, and at the end of every post/response they need to summarize all of the statements which they have Tokens invested in along with any changes they made during that post.
I think it could work and it wouldn't require people to be completely synchronous. It might do well with some sort of out-of-forum record-keeping on a wiki or something, but that's true of a lot of things. I wonder if I could refine the design down to the point where only the "end piece metadata" was necessary.
Well, it's a thought.
I don't know if you've ever seen Storium, but it's something you should probably look at. It doesn't provide the kind of gameplay I really want, but it at least expresses a framework for online gameplay connected to forum-style interfaces which is functional, and I think anybody interested in online, asynchronous/play-by-post role-playing games should probably have some experience of it.