Actually this was my brother's idea, and he asked me to help him write it, and I ended up writing it for him. Anyway...
apparently there are lots of ways to play Mafia; so this version is not the one where you have to make up a stupid alibi. Someone else can do that if they want. Anyway, basically there are at least two mafia, who kill the citizens, at least one doctor, who saves the people, and only one sheriff, who turn by turn, finds out whether the the people are mafia are not. The point of the game is to get rid of the mafia, unless you are the mafia, in which case you try to kill off the citizens. To start out, nobody knows who's who, except for the sheriff. This game is very silent between rounds and very loud during. I think you'll pick up on it pretty quickly.

Disclaimer: None of these characters are mine, they are copyrighted property of Square.
Final Fantasy IX
Plays Mafia

Ragtimer: Everyone, Heads down!! Aces are mafia, Queen is doctor, Jack is sheriff, and numbers are citizens!!!
Amarant: *looking up* …it's called a cart.
(the ragtime mouse hits him on the head with the TRUE.)
Ragtimer: That's right!! You get 1,000 gil, but I said HEADS DOWN!!!
Beatrix: *looking at the ground* …you men. Can we just play already?
Eiko: Yeah, really!
Ragtimer: Okay! Question 1!!
Zidane: You play mafia by asking questions?
Ragtimer: That's…(Kuja casts silence on ragtime mouse)
Kuja: Look, we're playing mafia. Pass out the cards. *casts dispel on the ragtime mouse*
Ragtimer: Yes, Kuja-sama. *Submissively hands out the cards*
Eiko: (after seeing her card) Aw…man!!
Everyone: Shhhhhh!!
Ragtimer: Mafia, heads up!! Who do you want to kill? … Mafia, heads down. Doctor, head up!! Who do you want to save? … Doctor, head down. Sheriff, head up!! Who do you want to know? … Sheriff, head down. Everyone, heads up!! … Goodbye, Beatrix!!
Beatrix: What?!! Nooooo! We haven't even started!! That's not fair!!
Zidane: Good grief, it's just a game.
Beatrix: So's war!! *leaves the circle in a huff*
Zidane: Ooookay.
Steiner: Poor Beatrix…*sobs*
Kuja: Well there's little evidence to go on in the first round, but I'd say Amarant is acting suspicious.
Amarant: What?!
Cid: That makes me suspicious gwok.
Hilda: *whispering* Dear, you're no longer an oglop.
Zidane: He's always suspicious. That's nothing to go on.
Eiko: Yeah! And Kuja, you're reeeeeeal suspicious! And I heard sounds over here when they asked for the Mafia!!
Kuja: ...that was probably you.
Eiko: *jumps up and puts her hands on her hips* What?! I'm not the mafia, you poopy head! I'm the good guy here!! How dare you accuse me!!!
Kuja: I didn't, but I will now. I hereby accuse Eiko of being the Mafia because she's being overly defensive and obnoxious.
Garnet: Hear hear.
Eiko: What?!! Okay, I get it! You want to have Zidane all to yourself!!
Zidane: All in favor of voting Eiko out raise their hands! *raises his hand enthusiastically*
Ragtimer: No voting until I say so! *hits Zidane out of circle with the X*
Freya: So…Kuja accuses both Amarant and Eiko. Is that enough for one round?
Kuja: …I never accused Amarant, but we can pretend I did.
Cid: No, no, you needn't get the Mafia all over your rear. I'll accuse Amarant. I can smell guilt from a mile away ribbit, and since he's just across the circle from me, there is no need to track it.
Hilda: ……
Zidane (who just came running back): Can we vote now?
Ragtimer: No!!! *wields X again*
Zidane: NO! *casts stop*
Vivi: …Zidane, that's my move. You can't cast stop.
Zidane: You just had to tell him that. *gets hit out of the circle again, but comes back quickly*
Ragtimer: Amarant, you have been accused of being suspicious. Defend yourself.
Amarant: …I'm not suspicious. (Zidane laughs to the point of tears)
Ragtimer: Eiko, you have been accused of being obnoxious. Defend yourself.
Eiko: I am not obnoxious!!! Kuja and Garnet are the Mafia!! I tell you, something's going on between those two!!
Steiner: Princess?!
Garnet: Naw uah!
Zidane: …Garnet's not the Mafia…
Ragtimer: No accusations during the defenses!! Who votes for Amarant? (everyone raises their hand except for Garnet and Kuja) Majority rules! Good-bye, Amarant!
Amarant: ….whatever *leaves the circle*
Ragtimer: Everyone, heads down!! Mafia, heads up!! Who do you want to kill? … Mafia, heads down. Doctor, head up!! Who do you want to save? … Doctor, head down. Sheriff, head up!! Who do you want to know? … Sheriff, head down. Everyone, heads up!! … No one was killed.
Zidane: Nice save, doctor.
Eiko: Thank you. (all heads drop) Anyway, after that attempt on my life, there is no doubt in my mind now!! Garnet and Kuja are the Mafia!!!
Zidane: No…*looks confused*
Garnet: Aw… come on! I'm being framed here!!
Kuja: Don't fret, Princess. It's quite possible that the Mafia figured that if Eiko were killed after accusing us, the blame would be shifted to us. Maybe even Eiko is trying to make us think she's the doctor when in truth, she is the mafia … Well, I'd actually put that waaaaay past her, but give me a break. I have sit next to her!!
Freya: Precisely. It's always the person you least suspect.
Cid: Hilda?!
Vivi: You mean it's Quina?!
Freya: Actually, I think it's you…
Quina: I no mafia.
Eiko: OH COME ON!! It's GARNET and KUJA!!!
Kuja: *rubbing his ear* See, there she goes again. I formally accuse Eiko of poor tact, impersonating a doctor, yelling in my ear, and being obnoxious.
Garnet: I formally accuse Eiko of stirring up trouble, a typical mafia move.
Zidane: I don't think it's Eiko…
Cid: Hilda?
Hilda: Yes?
Cid: Are you the Mafia?
Hilda: No.
Cid: Oh…okay.
Freya: I'm trying to accuse Vivi here…
Quina: Why you accuse Vivi? He not do anything.
Eiko: Don't accuse Vivi!! Vote for Kuja and Garnet already!!
Zidane: Why are you accusing Vivi?
Freya: He's too quiet.
Garnet: He's always quiet…
Eiko: Exactly, vote out Garnet!!!
Garnet: Wait a minute…
Cid: HOLD IT!! (Everyone shuts up) All right, who's been accused, moderator?
Ragtimer: Eiko has accused Garnet and Kuja, Garnet and Kuja have accused Eiko, and Freya has accused Vivi.
Cid: Fine. That is enough for now.
Zidane: Hold up!
Zidane: Man, you just have to mess me up…
Ragtimer: Garnet, defend yourself.
Garnet: What have I been accused of?
Zidane: Garnet is not the Mafia!!
Freya: Come to think of it, it could be Zidane.
Cid: There's definitely something going on between him and Garnet…
Steiner: Princess?!
Ragtimer: Ahem. Kuja, defend yourself.
Kuja: Well—
Garnet: WAITAMINUTE! I never got to defend myself!!
Ragtimer: You had your chance.
Garnet: But no one ever answered my question!!
Ragtimer: It is no longer your turn.
Garnet: *on verge of tears* But that's not fair! I was interrupted!
Zidane: Aw…I'm sorry, Dagger…
Steiner: *standing up, unsheathing his sword* You cur!!
Kuja: Sit down. (Steiner does) Anyway, my defense works for Garnet too. All I have done this entire game was accuse Amarant of being suspicious and Eiko of being obnoxious. I was proven correct in both cases. I do believe that it is more than feasible that either Eiko, who was not voted out, held a grudge and, failing to kill either Garnet or myself, both of whom accused her, due to the doctor's intervention, therefore pretends to be the doctor to get us voted out. The doctor is wise to remain silent in this incident. On the other hand, there is a possibility that Eiko actually is the doctor, and saved herself from the mafia, who picked up on the tension from the last round, attempted to kill off Eiko to draw attention away from themselves. In this case it would also have been wise for the doctor to remain silent. *he shoots a look at Eiko*
Cid: I see. But who would be that smart?
Kuja: My guess *again looks at Eiko* is that no one was that smart.
Eiko: Oh really?! Well, despite what you may think, mafia, you're just mad that I found you out!!
Ragtimer: Hold it! …Eiko, defend yourself.
Eiko: Thank you. As I was saying, even if it was not smart to reveal myself as the doctor, because we can regretfully only take out one of them at a time, it was a necessary move to reveal the conspiracy!!
Freya: …That's not the doctor's job; it's the sheriff's job. The doctor's supposed to try to stay alive as long as possible.
Eiko: Well, the sheriff is obviously not doing his job!
Ragtimer: Vivi, defend yourself!
Vivi: I-I didn't t-try to kill Eiko, and I didn't k-kill Beatrix…
Ragtimer: Who votes for Garnet? (Eiko raises her hand) Who votes for Kuja? (Eiko raises her hand) Eiko, you cannot vote twice! (X's out Eiko) Who votes for Eiko? (Kuja, Garnet, Cid, Hilda, Steiner, and Vivi raise their hands) That is majority.
Quina: I vote for Vivi.
Eiko: *running back to the circle* Did I miss anything???
Ragtimer: Goodbye, Eiko.
Eiko: What?! (several black mages come out and drag Eiko from the room)
Kuja: *sighs in relief and turns eyes skyward* Thank you.
Ragtimer: Everyone, heads down!! Mafia, heads up!! Who do you want to kill? … Mafia, heads down. Doctor, head up!! Who do you want to save? … Doctor, head down. Sheriff, head up!! Who do you want to know? … Sheriff, head down. Everyone, heads up!! … Goodbye, Cid!!
Cid: Of all the gwok nerve. *leaves*
Kuja: Who might do that? (all eyes turn on Hilda)
Hilda: Oh, come on. Just because he's a liar and a cheat and a lecher does not mean I would kill my own husband. (silence)
Quina: I hear her tell Cid she not mafia.
Hilda: Exactly, I wouldn't lie to Cid, would I?
Zidane: I just had a really scary thought.
Garnet: What?
Zidane: Quina could be the mafia…
Vivi: …I said that…
Freya: First things first. I accuse Hilda of killing her cheating husband, and I accuse myself of wanting to finish this round. Any objections?
Zidane: …I guess not.
Ragtimer: Hilda, defend yourself.
Hilda: Ditto Kuja?
Ragtimer: Freya, defend yourself.
Freya: Don't waste your vote on me.
Ragtimer: Who votes for Hilda? (All hands aside from Hilda's are raised) That's majority. Goodbye, Hilda. (Hilda smoothes out her skirt and leaves)
Ragtimer: Everyone, heads down!! Mafia, heads up!! Who do you want to kill? … Mafia, heads down. Doctor, head up!! Who do you want to save? … Doctor, head down. Sheriff, head up!! Who do you want to know? … Sheriff, head down. Everyone, heads up!! … Goodbye, Quina!
Quina: See? I not mafia! I dead.
Zidane: …
Freya: It's Vivi. Come on, he stuttered during his defense and he was trying to turn our attention to Quina.
Kuja: Hold it. Then why would he kill Quina?
Freya: …so we would think that?
Zidane: …
Garnet: No…I think Kuja has a point. That last killing was just random. Besides, you're still here, are you not?
Freya: Because that would not be a good move? Vivi's not stupid.
Kuja: Hmm…
Zidane: …I think it's Steiner.
Steiner: ???
Freya: What? Why?
Zidane: Because he's been avoiding drawing attention to himself the whole time. He's done absolutely nothing but try to act casually. Kind of guilty, like, you know?
Garnet: He has a point…
Steiner: Princess??? You are listening to that thief?!
Kuja: Huh. But would he kill Beatrix off the first round?
Freya: That's a good point too.
Zidane: That was a pretty good cover on his part…
Garnet: Doesn't sound like Steiner to me. Let's go with Vivi.
Kuja: We're running out of options, but I say close and vote too.
Ragtimer: All right!! Vivi, defend yourself!!!
Vivi: Aw…not again…I'm not the mafia. Y-you have to b-believe me. I stut-tter all the time.
Ragtimer: Steiner, defend yourself!
Steiner: I cannot believe, Princess, that you trust the words of a thief and his villain brother!
Zidane: Hey!! That's not a defense!
Kuja: Congratulations. I was going to vote for Vivi, but you have changed my mind.
Ragtimer: Who votes for Vivi? (Steiner, Garnet, and Freya raise their hands) Who votes for Steiner? (Vivi, Zidane, and Kuja raise their hands) Tiebreaker!! The defendants may not vote. Everyone else has to. Who votes for Vivi? (Garnet and Freya raise their hands) Who votes for Steiner? (Zidane and Kuja raise their hands) ………
Freya: Look guys, we need to get the mafia here. I'm sorry if Steiner insulted you, but we need to remain focused.
Zidane: Grrr…fine.
Kuja: *rolling his eyes* I change my vote to Vivi.
Ragtimer: That is majority. Goodbye, Vivi!!!
Vivi: O-okay.
Ragtimer: Everyone, heads down!! Mafia, heads up!! Who do you want to kill? … Mafia, heads down. Doctor, head up!! Who do you want to save? … Doctor, head down. Sheriff, head up!! Who do you want to know? … Sheriff, head down. Everyone, heads up!! … Goodbye, Steiner!!
Steiner: …Princess, I'm afraid it is too late to catch those scoundrels. *leaves*
Zidane: Not quite.
Freya: Are you thinking what I'm thinking, Garnet?
Garnet: …I'm thinking it's you.
Zidane: All right, listen up. We are down to four, so we have to get the Mafia on this next vote, or we lose…
Kuja: If we have that much…
Zidane: Ahhh, but we do. *smiles sweetly at him* Dagger, don't waste your vote on Freya; she's clean. Kuja's the mafia.
Freya: What are you trying to say?
Kuja: Just because I'm the antagonist does not mean I got an ace.
Zidane: No it doesn't, but the cards are down and you did get an ace. I got the Jack.
Garnet: Zidane, you're the sheriff?
Zidane: Exactly.
Freya: Hold up, Garnet…he could be bluffing.
Kuja: He could be mafia…Freya could be mafia…I'm more likely to think it's Zidane.
Zidane: Aw, geesh. Look, Dagger, he's stirring up trouble, like you accused Eiko. Only Eiko was the doctor, so we have to nail him now.
Freya: I think I'm voting for you, Zidane. It's a nice bluff, though, taking my side and all.
Zidane: Look, everyone I've checked has been clean. First round, I checked Garnet, then Eiko, then Freya, then Quina, and just now Steiner. It has to be Kuja!
Garnet: You checked me first?
Zidane: *scratching the back of his head* …yeah.
Garnet: *blushes slightly* I think Zidane's the sheriff…you should be a little more trusting, Freya.
Freya: Look, it's a game…but we must win. You can't let your emotions get in the way of your judgment.
Garnet: But…Zidane stood up for me in the first round…
Freya: So did Kuja!
Zidane: Geez…why can't you people believe me? Kuja does…
Kuja: I never said I believed you.
Zidane: Yeah, but you do.
Garnet: I remember now, his exact word were "Garnet is not the mafia." He said that twice, and then he tried to stop us from voting out Eiko, but Cid wouldn't let him so he got all frustrated. He's really the sheriff.
Kuja: Ai-yai-yai, is love blind…
Zidane: If she's blind, it's because she accidentally looked at you, sunny boy.
Kuja: Say what?!
Zidane: Hehehe, it doesn't need to be repeated.
Freya: Look, you two…
Kuja: Ha! I'll repeat your peat!!
Zidane: What?
Garnet: Freya, I'm voting for Kuja and you should too…
Freya: ……
Kuja: It's an insult I heard while passing a playground…I figured you'd understand it.
Garnet: He's quite capable of all of that you know.
Freya: So is Zidane…
Zidane: Great. Kuja thinks I'm childish and Freya thinks I'm dishonest. What do you think, Dagger?
Garnet: *winking* I'll tell you later.
Kuja: …we are getting nowhere fast.
Freya: Well, now that I think about it…it could be you…
Kuja: Me? You believe Zidane?
Freya: I guess I didn't want him egging me afterwards about how he tricked me. But you've been a little too helpful. That's not like you. You are hiding something.
Zidane: Although not much else.
Kuja: Look, I just wanted to win. Can I help it if I'm good?
Freya: I'm just saying it's interesting that the mafia let you live this long… and I think only you or Garnet would leave Zidane in this long… and—
Zidane: Look, stop thinking right there and vote.
Freya: I'll vote when I'm good and ready.
Garnet: Forget it. It's two to one. If she can't make up her mind, we don't need her, right sheriff? *she pokes his side*
Zidane: *laughing nervously* Right.
Freya: You're making a mistake, Garnet.
Zidane: If you don't believe me, Garnet might be the mafia. *he shrugs*
Kuja: They could both be the mafia…they're decent actors…
Freya: Then there's no point in voting.
Ragtimer: Zidane, your defense?
Zidane: I'm the sheriff.
Ragtimer: Kuja, your defense?
Kuja: Why? What's the point…I've lost…again…
Ragtimer: Freya, your defense?
Freya: Um, I'm not the mafia…
Ragtimer: Garnet, your defense?
Garnet: I'm clean. The sheriff said so.
Ragtimer: Who votes for Zidane? (Kuja raises his hand) Who votes for Kuja? (Zidane and Garnet raise their hands simultaneously) That is majority. Goodbye, Kuja!
Kuja: Farewell, Zidane…*leaves*
Ragtimer: Everyone, heads down!!!
Freya: …………
Ragtimer: The sheriff was…Zidane!!!
Freya: What?!
Ragtimer: The doctor was…Eiko!!!
Eiko: *from outside the room* Yaaaaaaaaaaaaaaaaaaay!
Ragtimer: The Mafia was…Kuja and Amarant!!!
Zidane and Garnet: Whaaa…?? (others re-enter room)
Cid: Good job, people! You got them!
Amarant: Kuja, you double-crosser! You cross-dresser! Wait'll I get my hands on you!
Kuja: Hmph. I personally do not want your hands within five feet of me. I just couldn't work with anyone who calls me a "sick narcissist" and then cannot define the phrase. I simply bit before I was bitten.
Zidane: I know what you mean…
Freya: So, Zidane, you really were the sheriff…
Garnet: *hugging his arm* Of course he was. Ne'er could my love speak false.
Hilda: So there was something going on between Zidane and Garnet.
Steiner: Princess?!