I've run a few RPG boards myself, though I tend to be a little more strict on my players than some other admins, so I dunno. I'd be glad to write the over-all story for the thing, since I've actually had a great CCS-ish RPG idea clunking around in my head for a while. However, I agree that we should wait to see how many people are interested... it is the very worst thing in my opinion to spend lots of time designing a game that no one plays.
Unfortunately all of my message-board RPGs are dead except for one, and I like to keep that one a little anonymous, however, if you wish to see the dead and dusty remains of the ones I ran before they can be found at:
http://www.tri-citiesanimefest.org/rpg/http://curiouser.proboards39.com/http://p219.ezboard.com/bclampschool34977 (this one never got beyond the very bare bones)
http://p216.ezboard.com/bcatchyoucatchme (this one is sort of based off of the idea I'd like to try to use here)
The other thing that is important for us to decide is how strict do we want to be with people? The more rules we require people to stick to, the more angry people get, though it usually ends up making a better story in the end... if you manage to keep enough players together...
Anyway, making a message board RPG is quite an undertaking, but I'd be glad to offer any assistance needed.