I've been playing some hidden role games lately.
Saboteur - Some players are gold diggers and some are saboteurs. The goal of the gold diggers is to build a tunnel from the start to one of three end points and find the gold, and the saboteurs are trying to stop this. The twist is that the first gold digger to find the gold gets a bigger reward than the others.
It's light and easy to play, but there didn't seem to be much gain in playing slyly as the saboteurs. The bad guys did best when they openly disrupted things from the get-go. Still, provided lots of laughs for our group of seven, and was very easy to teach (albeit the rulebook was a bit confusing at first. Much easier to have a veteran explain the game to you in 60 seconds than parse the rulebook).
Bang - I've had this game for over a decade, and used to play it with high school friends whose primary enjoyment came from trying to find ways to cheat or catch others in the process. This game has four roles: Outlaws, Renegade, Deputies and the Sheriff. The Outlaws want to kill the Sheriff, the Sheriff and Deputy want to eliminate all the Outlaws and Renegades, and the Renegade wants to be the last one standing.
The interesting bit here is that the renegade serves as a balancing mechanic. If the sheriff dies before all the outlaws are eliminated, he loses, so he has to play both sides a bit. It's a fun role to play, whereas the others can be straightforward at times.
The game provides some good fun, at the cost of relatively shallow gameplay and *gulp* player elimination. It's a light game you want to play with a casual crowd, but can result in players sitting out for long periods of time. Also, only one player acts at a time, so the time between actions can really stretch on (think EDH, but not so severe).
Resistance - Resistance solves the "lack of incentive to play in a tricky way" problem from Saboteurs and the "player elimination" problem from Bang. In Resistance, we have again two camps, good guys and bad guys, and a clear goal: win three of the five rounds.
Each "round", one player (this rotates) nominates a number of people to go on a mission. If the majority agree with the nomination, the mission happens. Otherwise the next person makes a nomination. Secretly, each selected player for that mission votes whether the mission succeeds or fails. A single "fail" vote sinks the mission (score one for the bad guys).
It's fast pace, full of deception, logic and deduction, and great. Unfortunately, the balance of the game highly depends on the number of players active, but there's a sequal Resistance: Avalon that I'm picking up this week which is supposed to solve this issue and make the game 5x better with some elegant new mechanics. It's the best group game I've ever played, and from what I've read, I can recommend Resistance: Avalon sight unseen.