Things I did like: The witness role. I hate the role of the investigator. He or she pulls names out of a hat and gets lucky when he or she finds someone worth noting. The Witness truly took the place of the investigator. Stupendous Man saw several things when he watched Khush on day one. It makes roled players think twice about who they choose to use their ability on. This role could be applied to either side of the game, too, to put some extra pressure on the townies.
Susie without the T-Rex. I still think this role seems perfect, but the inclusion of the T-Rex messed it up. His goal is to find his two players, one on each side, and keep them alive. When he finds the first one, barring some really clever foolery, he could just keep that one alive, too. I think a role like this has potential in other games. Because of how difficult it is to kill the two players, they would almost have to be victims of an attack specifically for them. However, I do think that perhaps the Susie role didn't need to be alive to win.
Calvin's Dad. Normally, protection has limits on uses, but I hate those. If someone has an ability, he or she should be able to use that ability regularly, and not have to pick and choose when. What would be different? I'd lower the vote total necessary to one or two, in order to make him more difficult to spot.
Adverse win conditions. The mafia hated them, but they barely affected the townies. I'd weaken the differences between the mafia and strengthen differences with the townies, and I think it would make for a wild game. One idea, as weird as it sounds, is to give the townie roles the standard townie win condition: Beat the mafia, but to give all townies without roles some wild win conditions. One would place the townie as a mafia wannabe, where he wins if the mafia wins. One would require that the player dies from the vote in order to win. Another would require a night death in order to win. One could say that the player needed two or three night actions to target him in order to win. One could tell the townie that he must start a bandwagon with at least five votes one day in order to win. The first few days would be very confusing for the townies, while the mafia would be pretty organized. I think this could make for a fun game.
And if Khush and I don't use it, I've got an entirely different way to play the game that I won't talk about now. I have no idea how it would go over, and I haven't planned it out, but it would be an experience completely unlike any other previous mafia game.
Oh yeah, back to the game: I liked the Spiff role. When working at full capacity, he could target whoever Calvin's Dad protected, Hobbes, and the player he wanted to kill, and either Hobbes or the player wanted killed would die. If hit, Hobbes could revive, and no damage would be done. It would allow him to target the specific player he wanted to kill with no chance of mis-fire. It would also take a lot of networking to do that, but it is a pretty cool possibility, none-the-less.
I like Rosalyn. Her role was remarkable. It was the reason why townies wanted to shut up about what they could do. Announce you're Hobbes? Well, Rosalyn could ruin your alliance check. Rumors of being the killer? Well, you may hit the wrong target tonight. I feel bad, because I thought Spak did this job perfectly, but still had no chance to win. Khush couldn't trust his investigations, Decoyman looked like an idiot. Stevey was the downfall of his own self. Don't forget, they could have shifted Pale's protection any time he didn't protect himself, and Pale didn't need to be alive to win, so there were a few times Pale didn't protect himself. I'm just saying that this role was pretty awesome, and it was used just as well as I could have hoped.
Mrs. Wormwood is pretty nifty. She has to die by townies figuring out who she is. The roled players can't check her out. No, she has to be fished out the old-fashioned way. She's a pretty powerful mafia role, in that way, since there's no night mistake to be made. The difficulty here is keep Wormwood a secret when she is a target. What do you say if she's been targeted specifically by an investigator? Townie or no info was returned? The key here was that Rosalyn was necessary. Since Rosalyn could just block an ability, it would seem like the player targeting the other player got blocked, rather than that he or she had found Mrs. Wormwood, which is something I had difficulty wrapping my head around at first, though it is what I went with in the end.
If you host a game of mafia, create one that you would like to play in. Make it something you think would be fun for you, and then each game should have something, maybe just a little something unique in it.