Or a BBS doorgame, like Tradewars or LORD.
Aral's picture drawing demo works by several kitten instances writing to a shared DB, right? Or is it just one instance with different users?
But it should be able to handle live messaging and player interaction at least as fast as that Goblins demo in the jam did, and stay up longer.
I think first is one instance with multiple users, enter commands and they get processed. Then federate it.