Without knowing what your particular definition is for something being a game, I really can't answer. Although
@EzekielRaiden did an excellent job of explain the core conceits of what
Fiasco is and how it plays.
I'd assume people's opinions on what makes a game a game would be wide and mixed, so even if my opinion is that
Fiasco is a game and thus rendered my point about it true... someone else could believe otherwise and thus claim the opposite. It's like the
Strong National Museum of Play having put the stick, cardboard box and blanket into the Toy Hall of Fame... they did so because children have used those items as playtime objects for centuries, but many people have said they can't be "toys" because toys are "made" and not just 'found objects'. And no amount of explanation would convince them otherwise of that. Likewise... everyone will have a different opinion on what makes a game a game.