Okay my turn:
Traitor Mafia
The game starts with 0 mafia, with all players being Townies. At any point in the game, a townie can send a PM to the mod saying that he is
Turning Traitor
. The first few players (up to 25% of the currently living players) become a vanilla mafia. At that point, any players who turn traitor become aware of the mafia's names, and win if the mafia win, but do not have the ability to nightkill. THe mafia also do not know who the traitors are. If the mafiates all die, all traitors lose the game.If 75% of the surviving players at any point are mafia or traitors, the remaining townsfolk become 'locked' into their roles and become a mason group with a shared vig ability.
There is a lynch every day, and there is a possibility that the game could be "Happy Ever After" after three days if no townies turn traitor. It will be interesting to see how players react to the stress of a tough game if they have the option of betraying town if things look tough. Also, the chance that the game will literally reverse itself at some point (Town being the informed minority) is also an interesting idea.