|Space is so cool.|
When life gives you a book filled with superpowered monsters and high-magic weirdos, you put them in space. You can only have so many high-level wizards running around before someone builds a moon base. It's self-evident.
Mordenkainen's Tome got me thinking about 5e, and this is the result. If we're going to go high-magic multi-species cosmopolitan, then by Jove we are going all the way!
The planets below are listed in order according to distance from their sun. Names have been changed to protect the delicate sensibilities of those poor IP lawyers, but you can figure them out.
Last note: you can help!
Yes, you! Simply head over to this spreadsheet and add whatever pre-existing D&D species or original aliens you want. There are plenty of examples already there, and I'm planning on making some big old tables out of it, so fill it up till your heart's content.
The universe consists of five primary parts: the Firmament, the Astral Sea, the Gods Themselves, the Twin Suns, and the Elemental Worlds. One might also find the City in the Center, the Great Machine, and the Clouds of Chaos within.
The FirmamentThe wall between the universe and the unformed Outside. It is, to mortal knowledge, unbreachable by science or magic, but cannot provide complete protection against the eldritch influence of the Old Ones. Those who approach the Firmament without adequate protection will begin to suffer deleterious effects upon their mental state days before reaching the wall, increasing with great intensity as they approach.
The stars seen on the wall of the Firmament were once believed to be holes that led to the Outside; recent expeditions have indicated that they are bioluminescent organisms tens of thousands of miles across.
The Astral SeaThe medium which fills the cosmos, a mix of aether and phlogiston in which float the corpses of the gods, the Suns, and the planets.
Unprotected exposure to the Astral Sea is not recommended for those who are not constructs, undead, or obscenely powerful, as it will generally involve one’s lungs acting very much like a combustion engine.
The Gods ThemselvesThey are all dead. Clerical magic is derived from their remnant sparks. Their calcified, ossified, mummified, fossilized corpses float in languid orbits around the cosmos. Their hearts, burning still with phlogiston, can serve as miniature suns. Most of the cosmic population lives on, around, or inside these divine bodies.
The Twin SunsThe White Sun and Black Sun chase each other around a central point. Each harbors orbiting worlds
The White Sun
EmpyreanA golden fractal puzzle box, resplendent and radiant, within which are the tablets bearing the words of the deceased gods. The angels and their associates are quite proud of this accomplishment, though no known beings have ever laid eyes upon the tablets, and their writings are unknown. The Cosmos beyond the White Sun
ElysiumBreadbasket of the White Sun system, every spare square foot of the planet is devoted to food production. The grids of meticulously-kept fields and fish farms can be seen from orbit.
HomesteadPleasant and pastoral, forever on the edge of the Industrial Revolution. Filled with a great variety of lands and cultures. Filled with legions of bright-eyed youths looking to make their fortunes in the distant reaches of the Cosmos. Considered a boring backwater by nearly everyone else.
HuxleyWhat happens when the unimpeachable State takes advantage of the population’s self-suppressing behaviors of pleasure-seeking, submission to authority, self-delusion and lack of long-term planning? Huxley happens. Do not stay too long, visitors are surveilled with vigilance.
MuirheimA dyson tree grown out of an ancient comet. Home and crucible of the great ecological movements, a close ally of the Kingdom Animalia on Zoan. The laws of peace and care of nature are enforced without delay or indecision.
High HrothgarChilly militarist fortress-world. Most of the planet’s industry is devoted to building war material to be used against the inhabitants of the Black Star. Technically aligned with Empyrean, the Hrothgari might be contracted by outsiders easily enough if the pay and glory is right.
ZoanUntamed wilderness world, home to the Kingdom Animalia. Off-world access is limited to a single spaceport atop a high plateau: any of the beasts may leave as they will, but outsiders are not permitted farther than the port without permission of the Kings.
The Black Sun
SheolWet, polluted scablands overrun with a singular species of underworld maggot. The planet is a soul-trap, stealing wayward souls mid-upload and embodying them in the gigantic larvae, to serve as a food source.
TophetA dumping ground for the Cosmos’ refuge. Continents of garbage, perpetually smoldering. Volcanoes oozing like zits. Unlikely home for high-end resorts and casinos, catering to the tastes of the decadently rich.
9 RingsA police-state ecumenopolis split into nine rival princedoms. Billions live in the lightless hives below the infernal nobility, slaving and warring away in ignorance of any other world or any other life. Order is maintained by an impenetrable bureaucracy, and the Princes’ inability to overpower each other.
XibalbaThe moon of 9 Rings, used as a prison for those the Princes wish to torment beyond the cruelties of life on the city-world. Is ruled over by six houses of demons shipped in from Grinding-of-Teeth ages ago.
Charnel HouseA scab-brown gas giant with a necklace of pocked iron moons. Constantly fought over by the forces of Grinding-of-Teeth and 9 Rings.
Grinding-of-TeethHomeworld of all demonkind. Scarred and broken continental shelves rise up above ocean bottoms now filled with everchanging jungles. The temperature fluctuates between boiling hot and freezing cold, the humidity shifts between oppressively liquid and dry as a bone. What water is left is mostly poison. Everything is attempting to kill everything else.
WailingA slightly large asteroid with a trace atmosphere, honeycombed with caves to the point that it is more like sponge than stone. The winds that flow through its inner halls form a constant keening moan, granting the place its name. The only people to live here are those who have managed to escape the other worlds of the Black Sun, but cannot find their way out. It is the last stop on a dead-end road.
The Elemental Worlds
AerosAn immense, pale blue-white gas giant, around which the other Elemental Worlds orbit. In the calm upper layers there are many floating palaces and sky-islands, where those without wings, sails, or flight bladders may live.
The Big EmptyA delicate spherical framework of diamond and graphene. Transparent habitat-bubbles house the wealthiest inhabitants of the Elemental Worlds, who praise a life lived nextdoor to complete oblivion.
ThundercrownA squat golden disc some thousand miles across. Its rim is thorny with thin protrusions. Lightning dances among its branches, arcing out across the aether to any ship that comes close. Exploration has been sporadic, and answers to its nature and origin few.
PelagiaA water world, spotted with young volcanic islands and tossed about by great storms. Beneath the surface one might find coral reefs a mile deep, thousand-mile kelp forests, and the single greatest display of biodiversity in all the cosmos. Boat cities, tropical hideaways, seabottom stations, and ice-cap settlements
NaclA small moon of Pelagia. Its shallow seas dried up long ago, leaving behind a dry expanse of salt crust and the fossils of what once lived there.
KettleThe second moon of Pelagia. A small rocky world with little atmosphere to speak of, its internal ocean strains to break free, and shoots up in great boiling geysers a hundred miles tall at times.
FimbulA world trapped in winter. There is just enough heat and light to support life, but the summer melts are still frigid to offworlders. Those who live here receive guests rarely, and with distrust.
The PitAn oozy, muddy slimeball; a dense atmosphere of mostly water and soil that has been reduced to mostly muck. Avoided by all who enjoy living in places that are not constantly and aggressively moderately unpleasant.
VaultThe greatest source of mineral wealth in the Cosmos. Mining conglomerates and banking families keep their home offices in the badlands, overseeing the stream of gold and gemstones pulled up from the depths.
TerragioA high-gravity terrestrial world, sculpted by the masterful hands of wind and water over millions of years.
ChokeThe moon of Terragio, named so for its near-perpetual storms of red-brown dust. It is a place for desperate types who wish to remain unnoticed and unseen. A planet of dry wells and ghost towns.
HaloAngelic travelers from Empyrean once settled here, but vanished generations ago. The world was shaped according to their whims and needs
PyreA desert world whose biosphere can exist without any water at all. The sands are brilliant bands of red and orange, and the skies are alight with hurricanes of fire.
CinderAsh and coals, nothing more. Smote to ruin for sins not even remembered.
BlacksmokeA greenhouse atmosphere of boiling black smoke drives off most visitors. Some spacers tell of a world hidden beneath the clouds, but rarely when sober.
The City in the Center
The City sits in the very center of the Cosmos, at the point both Suns and Aeros orbit around. It is neutral ground, a hive of scum and villainy, the cage in which god-killers are kept, the gate and key to all the Cosmos, and so on. You know the deal.
The Great Machine
There was a third Sun, golden-yellow. The progenitors of Machine-Life saw that it was good, and took it for their own. It sits now nested within a sphere of metal and law, all of its energy feeding the lockstep legions of mechanical beings who inhabit its boundless depths and vast chrome continents.
Clouds of Chaos
A roiling nebula of cosmic amniota filled with teratomatous, unborn worlds. Immensely dangerous to those that pass through without defensive preparations. Tracking their movements through the Cosmos falls to the Free Navigator Network - make sure to have it on your spaceradio presets!