? Townies
3 Masons
White Flag, Vengescum
Mafia wins if they make up half the remaining players
or
...Variant A: ...if all but one of the Masons are dead. If the penultimate Mafia is lynched, the game is over immediately as a Town win (no vengekill for that Mafia).
OR
Variant B: ...if all the Masons are dead. If the penultimate Mafia is lynched, they do get a vengekill, and if the last Mason is killed this result takes precedence over the White Flag condition.
Note that town wins if Masons ever outnumber Mafia, so this could just be an instant win condition as well.
Not sure how to balance this one yet, this is mostly a placeholder. I'm not even sure if town should ever claim anything, except when they have already reached an almost-won condition of Masons equaling Mafia - I will probably run EV with this assumption first. I'm actually not sure it's possible for town EV to ever be greater than 50% unless Masons equal Mafia, either.
Scumhunting in this one would be quite weird day 1, and maybe it needs to be coupled with a Bus Stop-like mechanism.