<Snipped quote by Aeonumbra>
I have a rough idea outline for a system that can solve a variety of problems.
- A user can mark a roleplay as one of their "Active Roleplays". There are various ways of enforcing this that I don't want to ponder right now, but it can include things like: you can only post in roleplays on your "Active" list, a GM with a roleplay open to applications must manually add players to the "Active" list before they can post IC, etc.
Having the requirement to be manually added to the Active list before IC posting may be a hinderance, unless it was a specific opt-in checkbox in the edit form. It would be useful for some RPs, but not all. (In other news, approving new entrants gives a new use for Co-GMs) For those without restriction, you should be automatically added to the Active list when you make your first IC post.
I can imagine the Active RPs system acting similarly to the Subscriptions system. In fact, the two lists may as well go on the same page. Of course, for some reason a user might not want notifications from all their Active RPs, only a few (once you add read/unread posts, of course). This can be avoided by keeping the two lists separate. The Active RPs list can be beneath the Subscriptions list, so it is only seen if you scroll to it (rather than the other way around).
Removing a user from an Active RP list should only be able to be done by that user themselves or a moderator. Otherwise you start giving GMs moderator level powers, which was agreed earlier to be not a good idea.