Choose one person to be the host of the game. If this person is you, tell everyone else to sit in a circle on the floor. Tell everyone to shut their eyes and put their heads down.
Walk around the circle and decide on three people to be the mafia in the game. The host taps them on the head to let them know they are the mafia. The host then says "mafia heads up." The mafia should silently look up and acknowledge each other, then decide which person to kill first. They silently agree, then put their heads back down.
Select the stool pigeon. This person looks up and the host tells the civilians, or those who aren't mafia, to raise their hands. Then the host tells the mafia to raise their hands. The stool pigeon then knows who they are without the mafia knowing who the stool pigeon is. The stool pigeon then puts his or her head down.
Tell everyone to raise their heads and announce who the mafia just killed. The person killed has to enter the center of the circle and enact a gruesome death for comic effect. They then have to leave the circle and cannot deliberate for the rest of the game.
Begin the discussion and debate. Everyone, including the civilians, mafia and stool pigeon starts arguing and accusing who they think is mafia. The mafia obviously want to keep their identities hidden and should try to blend in with the civilians by accusing others as well. Though the stool pigeon knows who the mafia members are, civilians often don't believe what they say because everyone else is accusing at the same time.
Take a vote from everyone for who they want to kill off next. The majority of votes decide who dies next. Sometimes civilians guess someone from the mafia, sometimes they guess wrong and a civilian dies. Again, they must act out their death in the middle of the circle.
Tell everyone to put their heads down again, and have the mafia choose their next victim. Again, they cannot use verbal communication to decide their victim. Once they've decided, they put their heads down again.
Tell everyone to raise their heads and announce the next victim. The victim acts out his or her death, then deliberations start again. This pattern continues until the mafia is killed off, or there are more mafia than civilians left alive. You then declare the winning team.
Start a new game and choose a new host. Each game is different and incredibly fun.