Many years ago--probably in the late 90s or very early 2000s, I became familiar with the GNS model, popularized by The Forge folks. This model, for those few gamers who don't already know it, posits that there are basically three "creative agendas" amongst gamers. The G stands for gamist, the N for narrativst, and the S for simulationist.
Because these words are, aside from their use in game design theory, in common circulation in the English language, many people (including myself) have used them in a manner that The Forge folks, who defined them in GNS theory, did not intend. This occasionally leaves one in confusion when discussing the finer points of game approach. Usually, context is sufficient to parse whether one means something in a particular Forgish sense, or in a more common English sense, but occasionally, it's frustrating. I saw an attempt one guy made to propogate some alternate terminology. I think that might have been a bit too much, but it wasn't necessarily a bad idea. For the sake of rambling, and because I haven't actually talked about gaming nearly as much as I used to, I thought I'd highlight the differences between how I often see GNS applied by those who are only sorta interested in the notion vs. those who are deeply immersed in the theory, and suggest some possible alternate terminology that you can use if and only if someone is confused and seems to struggle get your point. Well, on the other hand, there's no reason why you couldn't used the alternate terminology from the get-go if you like it better, although there shouldn't be any need to most of the time. But for those occasional times when you do need it...
Mostly, it's to talk about my own perspective on GNS, I suppose. I'm not really a Forge adherent. I'm not terribly interested in The Forge or GNS theory for its own sake, although I do quite like the notion of GNS as a kind of quick and dirty way to "bin" tastes or proclivities into various buckets. Because I tend not to use the GNS labels myself "properly"--or at least according to The Forge's usage, this might be a useful post to refer back to from time to time. And I can remember that I came up with alternative terminology if needed. If I'm talking about a simulationist tendency and someone takes issue with my use of the word simulationist, I can, for instance, say, "yeah, I'm using that term casually, rather than in a Forge specific sense. If it helps, maybe you can substitute the word 'emulationist' instead."
G - Gamist: A gamist element in The Forge refers to an element in which a player steps up and takes some kind of risk. Any time a player rolls a dice, for instance, that is a gamist element. Most gamers already assume some ambient level of gamism of this sort in their game (well, duh) so when they refer to gamist, they refer to elements that are too gamist. In other words, mechanics that are too "naked" and abstract, and therefore abrasive, and antithetical to game immersion. In other words (again) it feels like putting aside the game to play a completely separate mini-game within the game, which for many (myself included) find uninviting and undesirable. In this sense, "gamist" is a pejorative (unless, of course, you highly favor that specific style of game in your RPG) because almost by definition, at least as it's used, it refers to "too much gamism." If there's confusion, you could use the word gamey here instead of gamist. Gamey (to me, at least) usually is used in reference to meat. So, last week I made some chili with ground venison. I simmered the meat in a mixture of vinegar and lemon juice before adding it to the chili to reduce the gamey flavor in the meat, because for the most part, gamey meat is considered undesireable as a flavor. The same sentiment refers to RPGs that are too gamey. One could point to, for instance, the way spells work in D&D, or the way combat was handled in 3e and 4e, and call those elements gamey.
Exactly what is too gamey and what is not is a matter of taste, of course, but at least this way, it's not unclear what you mean if you call an element of a game gamist or gamey, or if you refer to a specific game as too gamey or gamist for your taste. Even using my alternative terminology--gamey instead of gamist, the word still starts with G, so the acronym doesn't change (yet.)
N - Narrativist. Narrativist in The Forge talk refers to the goal of allowing the players are more powerful role in the development of the game; mechanics that allow sharing of the "director stance" rather than the allowing the director stance to be exclusive to the GM, and the players acting in a more "improvisational theatre style actor stance" or somewhat. Very few people, when discussing the N in GNS actually mean this. What they usually mean is something much more in line with the latter; a stance in which a fun storyline, in which the characters themselves feature prominantly, and their decisions have meaning, and where in-game rewards might be subsumed to simply fun happenstance and whatnot, is prominent. Games that lack narrativism, in this regard, are games in which character background, motivation, and whatnot play no meaningful role, and stuff that happens in the game isn't meant to connect to any kind of narrative arc--either one pre-planned, or one that evolves natively as it happens.
In this sense, I'm highly narrativist (although I don't preplan narratives very much) but in the Forge sense, I'm not at all. A possible alternative terminology is Storytelling, which would change the GNS acronym to GSS (at this point.)
S - Simulationist. There is a slight difference between how The Forge and Everyone Else uses this term, although the difference isn't as stark, and there are few points of confusion around it. Whereas The Forge talks about simulationism as an ideology or game ideal in which all actions in game make sense from an in-game perspective, most folks use simulationism to refer to rules and mechanics that emulate a certain genre or approach. So, perhaps emulationist is a better word here. As an example--the monk class in D&D has a number of features that emulate wuxia kung fu movies. It emulates poorly, however, a grittier, traditional Eurofantasy environment. For this reason, many gamers find the monk to be a poor fit from a simulatist standpoint in D&D.
Does this mean that I've changed GNS to GSE? Maybe. Mostly, again, I'm just clarifying what I mean, and what I think most gamers mean when they use these terms, which aren't exactly the same thing that The Forge meant when they first coined them.