When I think about traditional strong-GM rpgs, I instinctively think of the game as being first and foremost a simulation that runs in the GM’s head. I see the GM’s model as the canonical reality — the real imagined space. Players then get a narrow, limited channel of access to it, via which they can build up their own secondary models (in their own heads) and exert very small influences on the simulated world (via their PC’s actions). But the GM’s world is the real one, the player’s mental models only shallow, limited reflections of it.
This is, of course, very much like how player clients access the server in a multiplayer video game.
That’s not the only model of rpgs I have access to. There are others, such as Baker’s “game as conversation” model, that I can use if I make the effort. But intuitively it’s the GM’s-head-simulation model that’s natural to me. If I don’t make an effort, it’s the model I gravitate back to. It’s the default lens I view gaming through. And I think it’s the mode of GMing that I most enjoy.
I don’t mean that I try to model the whole world explicitly — that way lies a grim madness. The vast majority of the world is uninstantiated until it’s probed — covered in a thick fog of abstraction. Up close to the PCs might be detailed, but a distant city might just me a name, location, and an image or two (“holy beggars with veiled faces”, “spike towers against the skyline”, “the guards are lazy and corrupt”).
I don’t prep that heavily — I’m often making the world up on the fly, out of nowhere. The “simulation” part is more about what happens once I’ve made something. NB this can be physical and close up (in a combat scene) or much more abstract. For example, for one current game I know there are 40 Archdeacons. I know that 20 of those are regional, 10 are at the seminary, and 10 work directly for the High Bishop. I have names and details for a handful that the PCs have interacted with. The rest are vague shapes in the fog.
Now, I often “make stuff up” by “looking in my head” and “seeing what’s there in the imagined world”. If the PC’s have just entered an abandoned building, and I’ve spontaneously said that there’s a hole in the floor, I might use my minds eye to “look into” that hole I just described and “see” that it’s an earthy pit dug six feet down to a broken minor sewer tunnel, about eighteen inches wide. And if I “look” inside the pipe I might see a man who’s squirmed in there, eyes wild and clothes in rags. I don’t have a sense of conscious “creation” there — it feels like I actually looked at something that exists. Now, I might edit the result consciously before I describe it (e.g. if the party are looking for someone, I might replace the wild-eyed man with that person), but I often keep most of what I see. Doing this feels like simulation, too.
I don’t mean that I use detailed battlemats and other tools of precise consensus — I never use miniatures, only rarely sketch maps.
I don’t mean that I use complex, detailed rules — I’d never willingly run Pathfinder, and I doubt I’d run Burning Wheel again either. The rules I’m running at the moment are pretty simple. I’m thinking of designing a game where most characters (including new or little-played PCs) are just a name and level. Indeed, maybe just a name (meaning that they have some default level).
I don’t mean to advocate for this model at all — What I’m saying here is that this is the model that is intuitive to me. I can think in this model without conscious effort. For other models, I have to make conscious effort, even tho I have been reading and thinking about diverse rpg theory for over a decade.
One consequence of that is that when I GM and prep using this model, I enjoy it more than when I use other modes.