Little add-ons to the game consist of playsets (Bully Pulpit is releasing one per month) that provide some ready-made setting and disastrous ideas off which to riff.
We ground the gears somewhat at the start, trying to figure out how the system worked, but eventually got ourselves into some fun trouble, what with the cooked books on the airport contracting job, the truckload of marijuana, assault and battery, crooked cops, the souvenir paperweight/live grenade, and all.
There's not much in the way of rules, but ultimately I found some of the rules opaque and distracting, rather than supportive of storytelling. It was very curious with this coming so soon after playing in Ian's improv rpg, the fictional plot of which could well be described as a fiasco of exactly the sort that Fiasco is attempting to produce. Very similar experiences in some ways, but I'd have to say Ian's game was more satisfying. Fiasco, on the other hand, provides enough scaffolding that it takes a lot less time to jump into the story.