Although my birthday was on the 10th, I had my party about a week later, on the 16th. The main reason for this was because of Mother's Day, I simply didn't want to put my guests on a spot.
In total, we had about twenty people drop by and party for awhile. Being the geek that I am, the party revolved mainly around board games and table top games. While we did run 2-4 different games at a time, there were moments when we all came together and played a massive game.
The staple massive party game seems to be Mafia, a game originating in Russia and possessing many forms and variations. We ended up playing two rounds of Mafia, also known as Werewolves, one time with a smaller group and another game with all but three guests (who showed up half way through the game).
The game is a battle between an uninformed majority and an informed minority. A quarter or a fifth of participants are randomly and secretly Mafia members (or werewolves). Usually this is determined by dealing different kinds of cards to people. After the roles have been assigned, everyone closes their eyes and then the secretive members open their eyes and meet for the first time.
After this, there is a process of nightly murders and daytime, public lynchings. The majority, called the villagers, call suspicion on various people for different reasons. The mafia members, pretending to be villagers, do the same. The villagers aim to accurate find the mafia members and lynch them through an open voting process. If there is ever a majority, then the player, mafia or villager, is dead and eliminated from the game.
The mafia, on the other hand, seek to become the majority. They do this through the manipulation of the lynching and by their nightly murders. The villagers win once they eliminate all the mafia members while the mafia wins by having their number be equal or greater than the villagers.
Some variations include special roles, such as a Psychic Seer, who can secretly see someone's allegiance by having the moderator confirm his/her guesses. There might also be a Sheriff or Doctor hidden among the villagers who can save someone if they were targetted at night.
The variation that most people are used to involves repeated nights where everyone goes through the cycle of one daytime lynching and one nighttime murder where everyone closes their eyes. This eyes close part is how the mafia members, Seer, Sheriff, etc, remain secret, with the moderator/narrator being the only person who knows.
However, this was not the original version of the game. In the original version, the only time people close their eyes was at the very beginning. Once the mafia members knew who each other were, everyone opened their eyes and the lynching began. Instead of just one lynching, there can be multiple ones: any time a majority occurred, someone died. As well, people can do an open vote to go to sleep, which is when the mafia will start their work.
Instead of having people close their eyes and having the mafia members point at their target, night time activity is done through a paper vote. Villagers simply wrote "Honest", "Villager" or something similiar while the mafia wrote the name of their target. The only time someone is murdered at night is when the mafia unanimously wrote the name of a single person.
The moderator reads the votes so that people's handwriting is concealed. It is through this vote that the villagers know how many mafia members are left to be lynched. The paper voting and need for unanimity also means that the mafia members need to find a way to communicate their target. However, these activities may draw attention, which is good for the villagers, who normally get next to no clues to go on in other version of the game.
The original version of the game features no special roles beyond Mafia and Villager. Besides being difficult to implement, the game is actually fairly balanced in the original version whereas other versions usually have a very strong mafia who are nearly guranteed a kill every night.
I think I prefer the original version over other variations. The only hassle is the paper vote. If only there was a way to pass around an electronic device that will scramble the order of the votes and then tally it automatically. Maybe I should make one...