Alright, let's take a different approach and think about the following:
The game of Mafia has lost its meaning long ago; currently it's a name for strategy games that use similar concepts like roles and phases and powers.
And...
It's safe to say that CM as a subforum has seen much better days. Mafia isn't the only game out there. Yeah, there was good reason to make this place Mafia Central a few years ago, but that era is clearly over.
So!
Whether we want to "revive Mafia" or not, what I have in mind is making this subforum an actual Circus Maximus. Like jumpluff said, there are plenty of people who would love to fool around and have a good time. They're not doing so not because they don't want to, but because this forum is dead and there's no reason for them to take initiative and immigrate here, especially when this is "a forum mostly for Mafia games, but Mafia is dead sooooo...". That, I think, is the problem.
The occasional YGO tournament is nice, but I'm thinking of casual fun that any user can jump into.
The Circus was a great example. That is how we can get a forum game subforum going.
If we DO want a hustling and bustling Mafia community back, that's a different story. We need to consider what we WANT in something like that, because the strategic game called Smogon Mafia is dead. I see two options: go back to traditional Mafia, or invent a new breed of strategy game, since that's the route this community has taken since multifaction games. We can't call that Mafia anymore, though - that's a worn out facade. It's a strategy game in CM, not Mafia.