My ignorance is showing here, but what is a “Mafia” thread or a “control” thread, and how does one participate?
It’s a game. One person is the moderator, everyon else is a player. 1-3 of the players are “mafia” or “assassins” the rest are citizens, and the moderator/gamemaster assigns that role and the general setting. You assign yourself your personality, but as far as the game goes it doesn’t matter (but many think that’s most of the fun). The citizens do not know who are the mafia, and the mafi work to conceal their ID.
Every “turn” the mafia tells the GM that they have killed one oher player. After that, the players vote to “lynch” one other player, hoping it’s the mafia.
There are variations. The mafia nearly always win.
Which thread/threads are you referring to? Because while Dr. Death has accurately described the real-life version of the game, there’s an internet-only version that gets played here a lot, and it’s a lot more complex. (Plus, the town wins about half the time.) But, those threads are in The Game Room, so…I don’t know.
Our internet version of the game tends to follow Dr. Deth’s link fairly well, although we tend to theme our roles with different names than are given in the above wiki link. Deth’s brief explanation describes the soul of the game, but each individual instance will have it’s own ‘flair’.
The game is more than a little intimidating to new players, but happily, there’s a newbie-oriented game that’s pretty simple signing up right now that follows Deth’s explanation fairly closely. I would have thought you would have known about that one, pedescribe. 
It’s strongly recommended that you either try to join that game, another ‘newbie’ game, or read through the first Mafia game on the Dopebefore engaging in any of the veteran ones. Fair warning: a game that takes an hour in real life can end up as a six week commitment on the internet.
LIES! Don’t believe any of them! They’re all trying to make you take their side. Don’t take their word for it, especially Boozahol’s.
Vote Boozahol.
I’m with pedescribe on this one, since we don’t really adopt different personas, nor do the Mafia usually win.
vote Boozahol
I was curious about the Mafia thread I saw for a long time before I actually ever clicked on it and took a look at the game. The best way to understand is to read one of the games. I cannot begin to tell you how many people IRL to whom I have tried to explain the workings of Mafia, only to be met with a blank stare, no matter how detailed the explanation. All they get out of it is, “I am a dork. Let me tell you why.”
ETA: What’s the voting threshold here? Are we about to start the countdown on Boozy?
You missed out on Autolycus’s Mafia playing days. Those were a blast.
And the Mafia usually does win. Well, when they have me.