I like the idea of the place acting like a series of memes but with continuity. So the setting changing every few months (or even specifying that you're using that setting even after the main setting has changed) but during those months CR and character memories carry over from post to post. So everyone is in a high school AU together for a few months, then suddenly everyone starts over in a sci-fi AU for a few months. But if people still want to make posts from the high school AU they can go for it.