RPGaDay 9: What is a good RPG to play for about 10 sessions?

I'd say most PBTA games (and in a lot of cases most games that share that design-space in the industry). You need more than a couple sessions to really get them going, but characters tend to resolve arcs after about ten sessions and lapse into a bit of thumb twiddling after that until they get pointed in a new direction – it creates a good point to wrap up and move to something else.

(Note, for 2 hour long Roll20 sessions with five players, triple all sessions-required estimates.)