Mafia: general discussions.

3. Games played by non-standard HeroesWorld rules.

I can suggest a variant.
4 teams of roughly 4 roles each. One or two (or even none) initially know their own (mafia players) - 3-4 roles, the others (or all) initially don't know their teammates (towns) - 4-5 roles, but have the right to find their teammates using "non-dark communication methods". Plus one or two maniacs. Each role has one (or several) attacking NPCs (in addition to others, of course) and some health pool. You could also add team NPCs (usable either by any player or by a specific role).
And instead of voting to hang a player, vote for some bonuses/penalties.
Some might think such a mafia doesn't even resemble mafia, but the games held here also have nothing in common with classic mafia of a sheriff, doctor, three mafiosi, and a bunch of NPC-less meat.;)

If there's a GM willing to run something like this.

I think a GM could be found; the real question is whether there would be players willing to play by such rules.;) For a required attribute of such games is an alliance and "diplomacy".