Quoting Mr Dancey

Interesting post from Ryan Dancey at the RPG site from October of 2007. This does a really good job of explaining GN&S theory in positive terms, while simultaneously pointing out the biggest flaw of such theory. I think his point is that GN&S theory identifies three reasons people game, but that only one of them is best satisfied by RPGs. The other two categories (G & S) are best served by other types of games.

in true "Big Model" theory, G, N & S refer to people, not games.

"Gamism" refers to a state of play where competition is the dominant value. Poker is a pure "gamist" game; nobody is narrating or simulating anything. The only thing you do is try to beat other people.

"Simulation" refers to a state of play where the point is to create a simple system to model a complex system, and then explore how that system responds to different kinds of inputs. Sim City is a nearly-pure "simulation" game; you have no opponents, and no victory conditions, and the point of playing the game is to see how many different results you can obtain using the toolset.

"Narrativism" refers to a state of play where the point is to create an interesting story. MOST RPGs strive to be narrativist games. Few have victory conditions. Very few have competition. Most use their rules mechanics to simulate the bare minimum required to facilitate the story, and abstract as much as possible.

Our market research did not find any significant clusters of people in the TRPG player network who expressed strong preferences for "gamist" or "simulationist" RPGs. They are all basically Narrativists. Our 2-axis graph serves to further subdivide the Narrativists, not to separate Narrativists from other kinds of gamers, or other kinds of game experiences.

Ryan, of course, has worked for Wizards of the Coast (and a few other gaming companies). The market research he references is no doubt the most widely sweeping and most thorough such research that has ever been done in the industry.

Personally, I think GN&S is really interesting and illuminating, as long as you take it with following grain of salt: Most gamers fall into all three categories to one degree or another.