A small group party game, Fiasco is the most inviting rpg I think I have played. There are no character sheets and every game is a one shot. It's more a session of structured improv than an rpg in reality.
I have played the game twice. Each time with 4 players. It's fantastic. It's great as a double date activity for us nerdy folk.
The downside to the game is that it is difficult to explain the concept to someone which can make it difficult to convince them to play. That being said it's well worth it.
[5 of 5 Stars!]