provide an end game mechanic
My biggest fear with Storium is that it'll sink due to the same problem PbP games have always had - they don't end, they just drift into disuse. Storium could compensate by providing an end game mechanic - if nothing else, a standard way to say "This game will last about 5 scenes", and (crucially) cues to narrators that that's the normal way to do things (i.e. finite games are the norm).

Storium games can now be set up using a 3-Act format with a visible ticker at the top of the game page to track progress.
Short Story: (2 / 3 / 1 scenes)
Novella: (3 / 6 / 3 scenes)
Epic: (4 / 8 / 4 scenes)
Custom: choose your own number of scenes per Act.
The 3-Act format is very popular and I believe has contributed to many completed games. Thanks!