The Forge, Ron Edwards' rpg game theory website, is no longer the powerhouse it once was. Early in the days of the internet, so much indie game design was influenced by this website. Probably still is, even though it shut down its forums nearly a decade ago. I know I still use lingo derived from The Forge when discussing game theory stuff simply because the one really good thing they did was set down a list of definitions that were clear and concise to discuss various aspects of role playing games.
GNS, and later the Big Model, though, was supposedly Edwards' crowning achievement. A theory of game design that posited the idea that all RPGs are composed of a combination of three modes of play: gamism, narrativism, and simulationism. Or, people make games to game the system, or to create a story, or to run an imaginary world.
But that never sat right with me. Partly, I think, because Edwards believed (still believes? I'm not in contact with him anymore after the destruction of Alderaan...I mean G+) that good game design focused on only one of these three modalities and sought to deliver a game focused only on that modality.
Enter Alexis Smolensk and his elephant. The linked post didn't receive any feedback directly in the form of comments, but Alexis makes the same argument in this post that I have made against GNS. A good RPG doesn't seek to cater exclusively to gamists or narrativists or simulationists. It needs all of them to be a good game. Hell, I didn't need Alexis to figure that out. But what Alexis does in the post is set out what some of the real modalities of play (creative agendas in Edwardsian/Forge lingo) are.
Escapism (distraction in Alexis' post)
Exploration and Discovery
I can add a few more, things like Immersion (related to escapism, but not the same), Wish Fulfillment, Camaraderie, and again I'm sure there are more. These are things players are looking for in a game.
Edwards wanted a tight little 3-part model. He also erroneously linked players' creative agendas with designers' agendas. They are not and should not be the same. Edwards' three agendas may or may not be pertinent creative agendas for game designers, but they really fall short when trying to classify reasons people play RPGs.
A well designed game should be an elephant. Different parts of the game should cater to different agendas, but all should be part of the whole. And as a designer, myopically focusing on only one modality of play really limits the design.
Oh, and Alexis at the end turns his post to his kickstarter menu project, which again I'd urge you to support. I'd like to see it succeed. He only needs about $700 (US) to fund it.