The Hollow World is a campaign sub-setting for the Dungeons & Dragons setting of Mystara, released under the Basic D&D mechanics system. The Hollow World, as its name implies, is a result of Mystara embracing a more pulp fantasy approach than the neo-Medieval approach of Greyhawk; it's a world that exists inside the hollowed-out center of the planet itself.
To expand on that... Mystara the planet doesn't merely have an Underdark, but it has an enormous hollow mass at the planet's center - picture the planet as a balloon made of rock and you've got the right idea. Aside from secret tunnels in the Underdark, it can only be reached through two huge portals at the northern and southern poles of the planet. Carefully developed by Ka the Preserver and an alliance of other Immortals, the Hollow World serves as Mystara's preservation grounds; every species and culture that has ever died out on the surface is preserved here, in eternal stasis, from neanderthals and dinosaurs to Blackmoor elves with their robot servants to the primordial Kogolor, ancestors of dwarf and gnome.
How Does It Work?
You're probably wondering just how this oversized petri-dish actually functions. On the one hand, it removes breeding populations from immediate dangers, but on the other hand, how does it preserve the cultures from changing or being wiped out once they're settled in the Hollow World proper? Well, that was something that Ka realized he had to address relatively early into the project, and he and his allies came up with a magical solution: the Spell of Preservation. This deity-tier working permeates the entirety of the Hollow World, and has several notable effects:
- Paralyzing Burrowers: One of the two main functions of the Spell of Preservation is that it traps the Burrowers - horrific aberrant monstrosities that almost destroyed the denizens of the Hollow World - in stasis, keeping them from doing anything ever again.
- Preserving Individual Cultures: The other main function of the Spell of Preservation is to inculcate a subtle but potent bias for one's own individual culture in the minds of all denizens of the Hollow World. No matter what you do, an individual from a given culture will always preserve that culture's traits, and will only pass on that culture. Cultural assimilation and extermination is effectively impossible, because you can never make a wide-scale change to the cultural traits of a given society. You can, for example, enslave a tribe of neanderthals and force them to serve you, but they will never stop using their Stone Age tools and will always secretly pass on only their original culture to their children. This aspect of the Spell isn't 100% perfect; some natives of exceptionally strong will choose to forsake their original culture, but these are rarities and will never be common enough to promote a wide-scale cultural shift.
- The Spell of Preservation also has two magical side-effects.
- Firstly, it forms a natural drain on the ambient magical energies; mages and clerics who studied above the Hollow World are unaffected, but the lowered magical background makes it comparatively harder for people to be born with the knack for magic (which mechanically manifests as needing a higher base Intelligence or Wisdom to qualify for spellcasting classes); this means that spellcasters are much less common and usually much lower-powered than they tend to be on the surface.
- Secondly, the Spell negates all mortal-level attempts at using certain magics, predominantly those that involve messing around with the planes (conjuration, certain divination spells, teleportation) or that involve controlling minds (most Enchantment and Illusion spells).
That said, the Spell of Preservation does have a few limitations...
- Cultures are NOT 100% Static: Whilst the general trappings of a culture won't change, specific aspects of that culture can and will change. For example, when the Azcans first arrived in the Hollow World, human sacrifice was the exception to their religious customs rather than the rule, but their own patron Immortal has coaxed them into making human sacrifice the norm.
- New Cultures Can Still Develop: The Spell of Preservation only cares that there is a stable breeding population adhering to the "template" set when a race is added to the Hollow World. So long as this "core" culture remains intact, new sub-cultures can still splinter away from the old one.
- New Life Can Still Be Made: The creation of new species or even sapient races does not directly endanger the existence of old races and cultures. As such, the Spell of Preservation doesn't interfere with such efforts.
Now, being a native of the Hollow World may sound like a pretty sweet deal... y'know, apart from being a glorified zoo exhibit for the Mystaran Immortals and any adventurers from the surface. But there are some pretty major downsides to this whole project. Even Mr. Welch, the legendary Mystara promoter, thought that the Hollow World basically fell apart when you thought about it too hard, and put together a video explaining why, which you can watch [over here].
What's the problem? Essentially, because the Hollow World took each resident culture at the nadir of its culture, they are trapped forever at the verge of complete and utter failure, meaning that they literally only continue to exist because they have a bunch of dedicated immortals who are working around the clock to actively reset things when they finally die out. The Gentle Folk are super-pacifists who literally have no survival instincts. The Blackmooor elves cannot grow out of their apathetic indifference to the world around them. The Brute-Men and Beastmen are stuck in the Stone Age whilst surrounded by more advanced civilizations. The Nithians can't grow out of being a bunch of backstabbing douchebags. The whole Hollow World project depends on the Spell of Preservation to keep them from just crumbling into nothing, and even then, it only works because the Immortals are constantly shoring things up by resurrecting the dead or switching civilizations to more hospitable points on the Hollow World.
Nations of the Hollow World
- Antalian Wastes: An Iron Age human culture of Viking expies that lives in the hard, frozen, mountainous regions of the northern hemisphere.
- Azcan Empire: An Iron Age human culture of Aztec expies that lives in the tropical rainforests.
- Beastmen Wastes: A Iron Age culture of igloo-dwelling polar hunters and fishermen who live in the icy lands that make up the northern polar region of the Hollow World. As their name suggests, they are Beastmen - the highly mutable ancestors of orcs, goblinoids, and ogre-kin.
- Blacklore Elf Valley: An isolated valley hidden in the southern polar region of the Hollow World, filled with indolent elves whose ancestors were rescued from the age of Blackmoor. As such, they retain the most advanced technology in the Hollow World... sort of. To keep it from getting out of control, the Immortals have actually replaced the technology with scientific-seeming devices that actually run on divine magic; the degenerate elves are too dumb to realize this.
- Brute-Men Territories: The regions populated by the Hollow World's indigenous tribes of neanderthals.
- Elflands of the Gentle Folk: A valley in the forested regions of the northern hemisphere, which houses survivors of the original proto-elf race. Trapped in the sickly, declining culture that other elves on the surface grew out of, the Gentle Folk are an example of the dark side of the Spell of Preservation: the Blacklore Elves have achieved nothing because they are lazy and stupid, the Gentle Folk are trapped in a decline that can never be recovered from nor ended.
- Elflands of Icevale: Icy hill and and mountainous regions south of the Beastmen Wastes and due west of the Antalian Wastes, inhabited by tough, lively, energetic elves who have an Iron Age culture that revolves predominantly around hunting and sports.
- Hutaaka Valley: A heavily agricultural Iron Age valley inhabited by the Hutaakans, devout and priestly jackal-people.
- Jennite Holdings: A culture of early Iron Age human nomads who inhabit the great plains and flatlands in the temperate zone of the southern continent.
- Kogolor Dwarf-Lands: Lush, beautiful mountains and foothills inhabited by the Kogolor, primeval ancestors of dwarves and gnomes.
- Krugel Horde: An inhospitable land of semi-arid plains, dusty scrub country and desert inhabited by nomadic tribes of somewhat Mexican-flavored orcish cavalry.
- Kubitt Valley: A hidden valley north of the Milenian Empire, inhabited by the Kubitts; 18" tall amazon warriors.
- The Lighthouse: A hidden mountain city populated by the collective scholars and mystics of the Hollow World, the one place where the Spell of Preservation is suspended and cultures freely intermingle, mutate and grow.
- Malpheggi Swamps: Primordial swamps and riverways inhabited by tribes of lizardfolk.
- The Merry Pirate Seas: An array of waterways, seacoasts and islands in the equatorial region of the Atlass Ocean, inhabited by a multi-racial culture of jovial swashbuckling pirates.
- Milenian Empire: One of the largest nations of the Hollow World, a pseudo-Greco-Roman human empire of Iron Age technological level that stretches across Southern Atlass ocean coastland and territories inland.
- Nithian Empire: A pseudo-Egyptian empire of Iron Age humans that concentrates itself along the shores of the massive riverway known as the Nithia.
- Oltec Hills: A Bronze Age culture of pseudo-South American Indians who inhabit the hilly forests on the southeastern verge of the Malpheggi Swamps.
- Schattenalf Caverns: A massive and sprawling civilization of
Drowevil Shadow Elves who inhabit the northern edge of the great equatorial mountain range where it meets the western sea.
- Tanagoro Plains: A Bronze Age culture of agrarian humans who live in the broad, grassy plains and forests of the southern hemisphere.
- Traldar Kingdoms: Essentially Bronze Age Vikings whose territory is based on where the great equatorial mountain range enters the Atlass Ocean.
- The Tribes of Neathar: Stone Age human tribes who can be found throughout the Hollow World.