I should give credit to everyone who contributed to the old M-Mars thread linked above, especially Chimpman. His planetary maps (linked in that thread) are what I'm using as a baseline, and the nation names largely come from there as well - either the map or the thread.
Noctaurus
by WingofCootReal-world Mars Equivalent: Noctis Labyrinthus
Origin: Taymora on Mystara
Noctaurus is a realm of canyons, mesas, and rocky hills -- a harsh landscape between the cold wastes of Tharsis, the waters of the Valles Marineris, and the spider-ruled desert of Mygalla. It is a militaristic empire in a largely barren land. Noctaurus is not terribly populous, compared to the other powerful nations of Vaniae, but it has the advantages of rich mineral and water resources, the great strength of minotaur soldiers, and the terrible powers of its monstrous rulers.
Demographics
Population: 90,000
Composition: 90% normal minotaurs, 5% winged minotaurs (<<1% vampire minotaurs), 5% other (mostly sandfolk)
Largest City: Arx Phoboi (10,000)
Other Cities: Oppidum Deimoi (8,000); Urbs Caeli (6,000)
The vast majority of the population of Noctaurus are ordinary minotaurs, except that their intelligence is somewhat greater than that of the minotaurs of Mystara, comparable to orcs. They serve as farmers, hunters, laborers, soldiers, and ordinary craftsmen.
Winged minotaurs form the nobility. These are as intelligent as humans and are responsible for the most skilled and valued crafts, as well as for directing and overseeing the labors of the ordinary minotaurs, serving as officers in the military, and administering the provinces and smaller dominions.
Some of the nobility are vampires as well - about 400 overall.
Non-minotaurs are either aranea spies or diplomats from Mygalla, giff mercenaries or traders from the eastern Valles Marineris, tribal sandfolk in the Western Province, or captured sandfolk taken in raids (either as slaves or for sacrifices to the Immortals of Entropy).
Government Structure:
Three great houses - Phobos (vampire minotaurs), Deimos (vampire minotaurs), and Caelus (living winged minotaurs) - rule the land. The emperor is chosen from among them (theoretically by election; in practice intimidation, assassination, and even outright war also contribute to the decision).
The current emperor is of the House of Phobos and has ruled for 200 years; his predecessor, of the House of Deimos, ruled for 1,500 years before being assassinated.
Each House rules a province of its own, nearly independent except for providing taxes and troops to the emperor. The other two provinces (Central and Western) are ruled by governors appointed by the Emperor.
Religion: Orcus is the patron Immortal of the ruling House of Phobos, so the worship of Orcus is the 'official' religion of the empire. In Arx Phoboi, the Emperor's own city, captured enemies, criminals, rebels etc. are often sacrificed to Orcus at midnight ceremonies presided over by the Emperor.
However, worship of Orcus is not required, and is rare in much of the Empire. The House of Deimos gives some attention to Orcus, as prince of the undead, but their primary patron is Thanatos instead. The House of Caelus favors Korotiku and is leery of many of the Immortals of Entropy, but they do give some lip service to Thanatos. The lesser nobility usually honor some combination of these three, as well as other Immortals of Thought or Entropy.
Common minotaurs usually follow either Thanatos (the sacrifices tend to make them leery of Orcus) or one of several Immortals of Matter. Their beliefs are rather informal and without ceremonies.
Clerics usually derive from the nobility, but rarely become truly powerful. (In BECMI rules, they are shamans; in 5E, they have normal cleric abilities, usually of the Knowledge or Death domains, but few rise beyond 4th level.)
Military Forces: Noctaurus has standing military forces composed of about 1,000 common minotaurs and 100 nobles. With the exception of the Emperor's personal honor guard, none of the nobles in the military are vampires, since they cannot fight in daylight.
Each city has a garrison, numbering about 2% of its overall population, and under the control of the House that rules that city and province. Other garrisons occupy castles in the Imperial provinces (Central and Western) or on the Mygallan border - these are under Imperial control, through a general appointed by the Emperor.
Each garrison is divided into units of 20 common minotaurs commanded by 1 noble. Smaller outposts scattered across the Empire in defensible locations support one unit each.
City Garrisons
Arx Phoboi - 200 + 10 nobles
Oppidum Deimoi - 160 + 8 nobles
Urbs Caeli - 120 + 6 nobles
Other Garrisons
Western Province - 100 + 5 nobles
Central Province - 180 + 9 nobles
Mygallan Border - 120 + 6 nobles
Outposts (total) - 120 + 6 nobles
Elite Units
Honor Guard - 10 vampire nobles
Frontier Scouts - 50 nobles
Relationships with other Nations
Noctaurus receives trade along the waters of the Valles Marineris, from the giff and gren nations to the east. Mygalla, to the south, is considered dangerous and untrustworthy, but overt conflict is rare (beyond occasional border skirmishes). The highlands of Tharsis block most contact with the west.
The minotaurs of Noctaurus are aware of, and very wary of, the Alphatians (Empire of Rabdriss), but have little to no contact. Still, the potential threat is one reason (beyond preventing internal rebellion / coup attempts by other Houses, and watching the Mygallan border) that Noctaurus maintains its military forces at this level.
Noctaurus is divided into five provinces. Three of these have the status of kingdoms, and are named after the royal Houses that rule them - Caelus, Deimos, and Phobos.
Populations -
Caelus
Total: 20,000
Capital and environs: 6,000
Capital city only (within walls): 2,500
Deimos
Total: 30,000
Capital and environs: 8,000
Capital city only (within walls): 3,000
Phobos
Total: 28,000 (27,500 minotaurs + 500 others)
Capital and environs: 10,000
Capital city only (within walls): 4,000
Central Province
Total: 7,000
Western Province
Total: 5,000 (1,000 minotaurs + 4,000 sandfolk)
Map of Noctaurus, with the five provinces labeled. EDIT: Scale of 24 miles per hex.
Phobos has the least sea-coast of the three kingdoms, but the large lowland valley that contains the capital is rich with life - green pastures full of livestock and fields making up great ranching and farming estates.
Arx Phoboi, the capital itself, presents a strong contrast to its surroundings. A grim combination of fortification and temple-city of Entropy, the walls built of massive stones rise high above the fields and the fishing villages along the coast. Within the walls, the streets of Arx Phoboi are all roofed - no direct sunlight ever shines in this city.
Giff mercenaries come here to take service in the Emperor's forces, but traders - whether giff or gren - rarely approach the bleak place. Sandfolk sometimes enter as captives, taken in conflicts in the Western Province, but never leave alive.
The Emperor uses no personal name. He is thoroughly ruthless and exceptionally intelligent. While proud of his power, he is aware of his weaknesses and always seeks to minimize/mitigate them. He does not truly trust anyone, but Vanth is almost an exception - before making any consequential decision, he listens carefully to Vanth's advice, even if he ultimately chooses a different path.
After 1,200 years of undeath, he scarcely remembers his natural life, retaining only dream-like fragments of disconnected memory. He disdains living nobles, and his attitude toward commoners goes beyond disdain to utter contempt. This view is strengthened by Vanth's influence.
Most importantly, he is a calculating planner who thinks on a time scale far beyond humans or even most elves -- he genuinely intends to rule forever.
The Emperor is unusually powerful. He is a vampire minotaur*, but his Charm has a -4 penalty to saves against it (or +4 to its DC in 5E terms), and it is permanent unless magically removed. An unique magical amulet gives him immunity to sunlight and also acts as a Ring of Fire Resistance.
Vanth, The Guide Unto Conclusion, is the chief cleric/shaman of Orcus in the Empire and the Emperor's personal counselor and most highly valued advisor.
Vanth was 'inducted' into the House of Phobos (changed into a vampire) 900 years ago. He was at the Emperor's side in the succession war. Vanth is utterly convinced that undeath is far superior to life, and that Vaniae is a dying world where life will sooner or later fail entirely. His great obsession is to discover a way that vampires can survive without feeding upon the living. If this were achieved, he would seek (with the Emperor's help) to transform all the living minotaurs in Noctaurus into zombies.
Vanth is a vampire minotaur* who is also a 7th-level shaman (BECMI) or cleric (5E).
*Vampire minotaurs use the statistics of a vampire, except have a minotaur's gore attack and can fly without transforming into a bat.
Deimos is the most populated province, though by a small margin, and somewhat less than it was 400 years ago when the House of Deimos held the Imperial Throne and the imperial court was centered in Oppidum Deimoi.
Oppidum Deimoi is a city divided. The inner citadel is a grim and sunless fortress, completely roofed over. This is the home of the House of Deimos and their immediate servants. The outer city, where living nobles owing fealty to the House of Deimos govern day-to-day matters, is sunlit and more spacious. Outside the wall of the outer city, fishing town "suburbs" line the coast, and farming villages extend up-canyon.
Deimos is almost entirely a broken land of canyons and mesas, lacking the cold northern high-elevation plateau of northern Phobos or the sandy desert of southern Caelus. Outside the immediate vicinity of Oppidum Deimoi, agriculture is unpromising and rare. But Deimos has a long coast, and most of its food comes from fishing and from hunting other water creatures.
Lady Deimos, like the Emperor, has used no personal name in many centuries. This terrible being ascended to the lordship of her House after her two predecessors were quickly killed in the succession war around 400 years ago. The need to consolidate her control over her own kingdom, along with Lord Phobos' superior ability to control minds, allowed Phobos to seize the Imperial throne.
Lady Deimos was a relatively 'new' vampire when she attained the throne, which led to the difficulties she had consolidating her control (along with the very short reign of her predecessor, about two months, and the instability resulting from the ongoing war). She has been undead for "only" 450 years.
Lady Deimos has the ordinary abilities and statistics of a vampire minotaur, except that she is extremely intelligent (INT 18). She is a patient planner, with many schemes in motion at once. She intends to topple the Emperor and claim the throne for herself, but is willing to wait centuries if that is necessary for success to be certain.
Caelus retains historical prestige, as it was the location of the first minotaur settlements in the Noctaurus area and the home kingdom of the first Emperor of Noctaurus, but its real power is now vastly diminished. Its population is the least of the three kingdoms (though more than the two imperial provinces). It produces food from both farming and fishing.
The living nobles of Caelus greatly fear the charm ability of the vampire nobles. Their enmity with vampires has largely led them to reject the Immortals of Entropy and follow those of Matter instead. They rarely go anywhere without mirrors and holy items blessed by a cleric of a Matter Immortal; most carry a few flasks of holy water in a belt pouch.
Caelus is the friendliest province to giff and gren traders, and other outsiders, though it is less wealthy than the other kingdoms.
The south of Caelus is sandy desert, bordering on Mygalla. An imperial garrison is stationed at its southwest limit.
The Central Province's small population of 7,000 consists of a few villages and a town centered around a stronghold, placed in a valley forming an oasis of rich life amid a desolation of canyons and mesas. These villages live by fishing in the valley's lake and farming the soils enriched by ash from the cinder cone to the north.
This is an Imperial province, governed by a military governor – the commander of the stronghold's garrison – who is appointed by the Emperor. This governor is chosen from one of the less powerful noble families that were vassals of Phobos even before Phobos held the Imperial Throne. The current governor, Marak (a living winged minotaur), is under the Emperor's mental control and therefore completely loyal to him.
The stronghold here – Lasthold - was built about 1,300 years ago during the Alphatian imperial expansion on Vaniae. It was built as a fallback for the Emperor and his elite forces in case of an Alphatian incursion through the Valles Marineris waters, which are connected to the canal system; 100 miles of Noctauran terrain would be an almost insurmountable barrier to any land force.
Western Province: Despite the presence of an Imperial garrison, most of the Western Province is not really effectively under Noctaurus' control.
The only minotaurs here are the garrison (of 100 common minotaur soldiers and 5 winged nobles) and a village surrounding it and supporting it (of about 500), and those living on ranches and farms spread out around the area within a dozen miles or so (totaling about 400 more minotaurs) – outside this area, there are no minotaur settlements.
The western part of the province is home to about a dozen sandfolk tribes, totaling around 4,000 individuals. A low-intensity but centuries-old conflict goes on here between the sandfolk and the imperial minotaurs. Small skirmishes occur regularly, usually several times a year.
The garrison stronghold (and province) was established around 400 years ago as part of Phobos' consolidation of power after the succession war, beginning the conflict with the sandfolk.
Like the Central Province, the general of the garrison also serves as governor of the province, and is chosen from a less powerful noble family among the long-term vassals of Phobos. The current general and governor (Lukach) is controlled by the Emperor's unusually powerful Charm ability.