There is a saying that adjectives don't add something they limit it. A book could be any colour until it is a green book.
Is "unlimited" an adjective?
Yes, there can be infinite worlds in the prime material, but how is that of any use? When something can be anything it is also nothing.
Well, for one thing, it opens up the possibility that
everything is possible for the PCs in “the Prime Material Plane”. If, for argument’s sake, one decides that the outer and inner planes are MotP creations after the Gygaxian fact, then it stands to reason to argue that a) they were created in the first place, b) that they can be created again, and c) that it can be you who does the creating.
For two things, I find it interesting to consider why and how MotP “canonized” things and how this sort of mirrored what our own group ended up doing.
“So we’ve all been telling these stories and making up people and worlds that have, um…, persisted. So how do we
explain all of what’s been happening so far? How is it possible that people can go wherever they want whenever they want? Let’s see what we can work with and build on that. So, since it’s D&D, what do these books ‛ere have to say about all of this?”
Tertio, if we accept MotP as canon and assume that it came about as suggested here, I find it rather interesting to realize how it goaded us into this particular train of thought, strain of reality – how it limited us in our thinking. Now, since, MotP purports to explain
reality and everything, and you abandon all of that, you effectively get back out of the rabbit hole the way you came and free yourself of the limits your way into it put on you – liberate yourself from your own way of thinking. That makes the possibilities endless and not just in a planar or dimensional way – for planes and dimensions do not exist any more.
Fourth…, well, fourth is actually fourth and fifth, each a topic I probably cannot discuss in ENWorld’s grandma’s parlor, unless she is, let us say, rather… latitudinarian about
a number of things. So I suppose I shall have to limit myself to one of them I can probably get away with and that is that it has been said that the whole concept of “gods” sprouts from the minds of the people that believe in them as opposed to that they actually exist. So, if one of these deities is seen as the creator of our world and we actually created that deity, then I’d say we’ve come full circle.
Sixth, it allows for the notion that “planes” are actually “creations” rather than things that exist in their own right and therefore cannot be denied, which one could argue is actually true. This, in itself challenges the PCs’ concept of “reality” and allows them to “create” whatever they want –
i.e., visit any plane they want to. Interestingly, that makes the concept of “planes” instantly superfluous – and with it the concept of “reality”.
So, in light of all this, if we accept MotP as canon for a “real fantasy world”, the step to considering that our own world is a creation of ourselves is easily made – IMHO, YMMV, WTL, etc., etc., and so on, and so on. Now, if one argues that the fantasy world – an imaginary world – is the creation of the PCs and that the real world – the real world – is likewise a creation of the people in it, then the distinction between a fantasy world and the real word is instantly gone.
This challenges the concept of what is “real” for both the PCs and the players, puts the concept of “self” in a wholly different light, compels them to think outside of the box, frees them from the limitations put on them by how the game evolved, and may ultimately allow them to do whatever they want at any given moment.
And that, I think, is a rather interesting concept.
For what are we doing when we are playing D&D? We are creating people in a world we create with our minds, which is as real to the PCs as the real world is for the players. I bet there’s a whole load of us who’d give a lot to actually be their at least one of their PCs, to live in the world they create, perhaps if only for a moment. Here we all are, sitting at a table, acting in a world that “doesn’t exist”, wanting to be there ourselves.
Perhaps one of the key concepts in all of this is that “we” are actually living in our own “creation” – the world as “we” know it. So if “we” can do
anything and everything, can we then not, at some point, reach a stage where we actually become our PCs?
Hmm… I did say all of that out loud, didn’t I?
Perhaps it’s time for some coffee and to go find my cat.
Oh, and I may have to start converting my shed into a weird-smelling room.
On a more serious note [sic], I have created one of my worlds as per the principle that everything in it is the result of humans having created it, which includes themselves. Yes, it’s an anthropocentric world.
Does that mean there are no planes as per MotP? No elements? No gods? No reality? That the “Prime Material Plane” has no limits? Well…, yes and no and therefore no and yes.
So can the PCs do anything and everything they want in it? Nope. Not until the
players realize that they are, in fact, their PCs – and forget about it at the same time.
Yes the outer planes limit things but in those limits they add details and themes for creating interesting stories.
Absolutely true. And I've run and played in many memorable adventures in the planes.
Edit: Last minute correction.