I wouldn't mind a 1 v (number between 4 and 12) type of mafia game, but something like this:
In a 12 player game, there is:
1 Enemy. The Enemy has three "magical" or "heretical" abilities, one choice and two random. Some can only be randomly taken.
2 Psionics. These are similar to the enemy, but all of their abilities are random rather than chosen. They are magic, but aren't killing people.
9 Humans. Humans get no abilities.
---
Also:
For every 3 players, one will be chosen as a VP, or Valuable Player. Valuable Players have abilities picked at random such as having actions at night, having extra day-actions, or other abilities such as surviving attacks.
For every 6 players, one is chosen as a Hunter. Hunters are special VPs that have a gun, body armor, and limited magical powers, and are the main enemy for the Enemy. They can always survive one night attack, and can shoot people in the day. There is a chance that their action will be silent, and it won't be known who killed who.
This game breaks the norm in a few ways.
1. Items can be stolen, and roles are not strictly enforced. A random villager could always try and knock out the Hunter and take his gun, and assuming he dosen't get caught then he can shoot anyone he bloody well pleases.
2. The Enemy can engage his powers at any time, but gets to freely try and kill in the night. Night is handled like any other Mafia game, but day is almost open-world. The Enemy's abilities also affect how kills are accomplished, such as an Enemy who can control fire, turn into a hawk, and become invisible could burn someone's house down in the night, or hide, become an invisible hawk, and attack during the Day if people figure them out.
3 Some enemy abilities completely change the game, such as Viral ( all game-mode changers can be selected by the Enemy ) which converts targets into loyal subjects of the Enemy rather than townsfolk.
Basically day is an openworld RPG, and night is abstracted.