I was reading a very interesting post by Mike Mearls the other day about dropping the structure of the planes in favor of something more local. Read his post here, http://kotgl.blogspot.com/2010/01/kill-planes-abyss.html.
I think his reasons of course are sound and fit nicely with something I have wanted to do forever. When I first picked up that 1st Ed copy of Deities and Demigods I loved the Planes. It had so many interesting places and so many things to do. I got very attached to the Great Wheel cosmology that I began to evaluate fantasy and later horror on how closely it fit that model. Then I began to get lazy. Not in the sense that would not write, quite the opposite, I would come up with elaborate schemes to make things fit the model or not. Whether it needed to or not. Even in my AD&D Grand Opus Adventure the characters went to Hell to confront the evils that invaded their world there was still the Great Wheel. It worked, then, but now I feel it's limitations. Well along came 3rd Edition and suddenly the planes are mutable, changing and even expected to be different depending on how you look at them; 4E changes this even more.
Mike Mearls mentions in his blog that one of the issues of the planes being "out there" that they lose some of their value. History tells us that demons, devils and other bad things came from under-ground, or beyond that mountain or from across the sea; here there be monsters. Monsters come from "beyond the sky" in Lovecraft related fiction, which is fine for tentacle horrors, but devils at least are concerned with the same things humans are. Devils need to be close. They need to be something the common man, woman and child fears. Not just because they are evil, but because they are nearby.
Mike says move the Abyss to your world, I say move Hell.
Hell in 4e now seems to be a planet floating somewhere in the Astral Sea. This puts it on par with everything else, even Heaven. Now I am not a religious person, but doesn't Hell lose some of what makes it Hell if it just a planet with bad environmental conditions? They describe it as planet some 7,000 miles in diameter with the "layers" lower and lower subterranean continent sized caverns. Like Mearls, I say take all that and shove it inside your world. Drill down a few hundred miles and there is the entry way to Hell. Just like Dante described. What keeps the devils in? Same thing that keeps them there now, gates. Like the roach motel it is, it is easy to get, impossible to get out. Or nearly such. Of course the point between the Underdark and Abyss sharing a nature is sound, I think I can get the same thing with the Nine Hells really. In fact I might even make Lolth more like a devil (she is more devil like than demon like anyway) given her status as former Goddess, cast out and down. Sound familiar? It certainly fits with what Hell is supposed to be better, an underground dungeon for the damned. The Abyss is a maelstrom of evil and chaos, it fits better in the planes.
Of course this is not without issues. First, and the one that concerns multi-versal games the most, is that Hell inside a planet means that for every copy/twin/multiverse that planet is in there is a corresponding Hell. This might be fine really. I don't care for some of the changes made to some of the Arch Dukes in the last few books (3 & 4), but I can write that off as that is just the way things are in that universe. Which is something we all do anyway, I am just making it explicit. Of course the new 4e cosmology also gives us the Shadowfell and the Feywild, which I like, but if they are dark and twisted reflections of our own world then what about the Hell for those worlds? I say that their Hells are ours. That if you drill down in the Shadowfell you end up in the same Hell as if you did it in the Feywild or the campaign world.
Back in the day there was a great series of Dragon articles about the various Arch Dukes and Dukes of Hell. The article began with a bit of fiction about a Paladin (a holy warrior for good) marching on to Hell to defeat evil at the source. This scene works better today than it even did then with Devils now generally evil rather than exclusively "Lawful Evil". And it works better if the Paladin is marching to Hell, not paying a wizard for an Astral Projection spell.
Sure *where* it is physically located might mean little to PCs and DMs with access to magical means of travel, but the world should make sense to normal people too. What is there to fear about a creature, evil and immortal or not, if it takes a great amount of magic to get them here.
Gygax was a reader of Dante, Milton and of Ovid. These authors, as much as anything and maybe more so, shaped what we think of when we think of Hell. "Planet Hell" inside the Earth/World then fits very well with all these writers. More than a plane "out there" somewhere. Which does bring up an interesting point. Here is a quote from Milton's "Paradise Lost",
"Orcus and Ades, and the dreaded name Of Demogorgon."
— John Milton, Paradise Lost II. 966.
So. Lucifer is cast out of Heaven and down into Hell, he meets up with these demons in some…what, ante-chamber of Hell, a place where Chaos rules with Night. Sounds like the Abyss, but where is that again? I have often wanted to merge Hell and they Abyss into one place where demons are the masses of creatures and devil are the upper-class. If I put Hell inside my world (or the Abyss like Mearls) then do I have room for both? Do I need both? Are they the same thing with different names? Then there are other issues I have avoided because of the aforementioned laziness. Tiamat is described in myth as "chaos" and her body is destroyed to make the firmament of the Earth. But then she gets tossed into Hell? Sure, it fits the outcast god model, but Tiamat is chaos. Lilith is also cast out, but she wants order, her own order, but order all the same; at least that is how I read it. Grazzt looks like a Devil, but is a Demon or maybe he is not. And there is the bit from Milton. So what is a world builder to do? And where is this antechamber of Hell were Demogorgon and Orcus act as the Welcome Wagon for Lucifer and the cast out Angels, now Devils? Hell has the River Styx, where the souls of the dead are ferried across, but now the souls of the dead move through the Shadowfell. This makes me want to break out the WitchCraft RPG seprioths and see if I can't make it all work.
Well here is my stab at it. The Antechamber is of course the Underdark. It is hundreds of miles below the surface of the planet. Here in the deepest pit was where the fallen angels were cast. It is here that they meet the demons. There is a great battle, Orcus (then a dark god) is killed only to come back from the dead, Demogorgon has his head cleaved in half (to regrow as two heads) and Ades…well that was the last anyone heard of him. The devils (as they are now known) take the realm once controlled by demons. Once there though the devils discover that Hell is not the home of the demons, it was only the realm they could control this close to the world. The devils seal the opening to the Abyss, place Tiamat there to guard against demonic entry and the devils themselves descend lower into Hell. Physically the Abyss and Hell (and Tarterus and Pluton and Gehenna) are all the same place locked deep within the Earth in a area were the Prime Material, Shadowfell and Feywild all intersect. The nine layers controlled by the Arch Dukes and Devils is known as Hell. Everything else is simply "The Underworld". The conditions are, well Hellish, it is inside a planet afterall, but great and powerful magics keep the denizens alive, though it warps other magic and prevents them from escaping. The areas known as the Abyss are open and there is much fighting, the area known as Hell is gated. It is supposed to be a prison after all.
At the bottom there is a dark chasm who feeds into the elemental chaos. I like the description of the Abyss in the new Manual of the Planes, it makes it sound like a black hole in the Astral.
It needs some work to be sure. Demons, like Demogorgon, Orcus, Pazuzu and others have more interest in human affairs than the mindless hoards of demons because they are more devil like, and thus, more human like. Older demons such as Dagon are more elemental chaos. Even Tiamat now is more demonic than diabolic. This helps explain the Bloodwar a bit better, explains the similarity between demons and devils and why in popular parlance (in the world) they are often confused. It also helps explain why some seem to switch sides every now and then. Or simply put, devils are the cast out immortals of good that betrayed or otherwise became evil. Demons always were evil.
Of course I could keep the Abyss as is in 4th Ed. There are plenty of good reasons to keep it in the elemental chaos in the Astral. Demons are more elemental, more chaotic obviously and more alien. Of "demon" can just be a term to refer to anything that is evil that is not a devil. If I go that route then "Devils" would refer only to the Fallen and things like Ice Devils, Malebranche and the like are demons, just a different kind. After all, Succubi were demons and now they are devils, so it's not like there isn't precedent.
What does removing the demons and devils from the "outer planes" rob us of in D&D? Well, Planescape to a large degree would need to be rethought. To a lesser extent the nature of Tieflings will need to be changed, though maybe not. Typically to get to those outer planes takes characters of some power, so there is the build up to go to their home turf and fight that is now gone; ie. anyone can find the opening to Hell and stumble in.
OR maybe demons come the "Hells" of the Shadowfell and Feywild.
Of course there is one huge advantage of reshaping the planes. I can shape them in a way to work with either my 4th Ed game or my OSR/Basic game or even something like Ghosts of Albion.
That is the fun thing about fantasy cosmology, it can be a mutable as I need it to be.