In terms of what's "real" in the imagined game world, I'm gonna take a crack at how I see this playing out.
So, everybody's imagining this fictional place where the events of the game are occurring. This might be as simple as how when you read a book you're following along with who's what, or it might be a full blown "immersion" where you're focusing on imagining your character, and only thinking about world stuff as they directly interact with it.
One school of thought might say that the "real" version of the imagined game world is in the GM's head. The GM tells you stuff, and that goes into your own version of the imagined game world, the one that's about your PC.
Another school of thought might say that the "real" version of the imagined game world is the shared one. What? A "shared imagined world"? Well, if you have a conversation with five people about a funny thing that happened yesterday, bam, that's also a shared imagined situation, so the whole idea of "this imaginary thing exists in all our heads simultaneously" isn't that weird.
The shared version basically says that the fancy, detailed version of the game world in the GM's head is the potential game world. There's all this stuff he has planned and prepped. But until it's shared, and the whole group is aware of it, none of it actually exists.
So really I think it boils down to where you think of the "game world" as residing. I personally think of it being the "shared imagined world", because that's the one everybody has access to.
So, everybody's imagining this fictional place where the events of the game are occurring. This might be as simple as how when you read a book you're following along with who's what, or it might be a full blown "immersion" where you're focusing on imagining your character, and only thinking about world stuff as they directly interact with it.
One school of thought might say that the "real" version of the imagined game world is in the GM's head. The GM tells you stuff, and that goes into your own version of the imagined game world, the one that's about your PC.
Another school of thought might say that the "real" version of the imagined game world is the shared one. What? A "shared imagined world"? Well, if you have a conversation with five people about a funny thing that happened yesterday, bam, that's also a shared imagined situation, so the whole idea of "this imaginary thing exists in all our heads simultaneously" isn't that weird.
The shared version basically says that the fancy, detailed version of the game world in the GM's head is the potential game world. There's all this stuff he has planned and prepped. But until it's shared, and the whole group is aware of it, none of it actually exists.
So really I think it boils down to where you think of the "game world" as residing. I personally think of it being the "shared imagined world", because that's the one everybody has access to.