Horos (Greek for “limit” also sometimes called “Arch” in various languages, since the horizon to the east and west is an arch sweeping upwards. To the north and east, there are great walls of blackness, or the sun, depending on the time of day.

Horos is a “Bishop ring”–a megastructure of a flat cylinder, like a wheel, which is tilted a bit relative to its orbit around the sun. It lacks any satellite (tides might be generated by precession). Spokes run towards a central Hub (which is always covered by clouds–there are also lower, normal clouds). [Do the spokes run from the edges only or are they more like a bicycle wheel, where spokes alternate angles for more strength?]

A dying race of titans sent forth these worlds, of which Horos is only one of many. They knew they would not themselves survive as a species, seeking only that intelligent life could carry on somewhere. The rings are bio-engineered, living things themselves, designed to foster life. Horos was tended by Animothros, apparently alone.

The Kin, anthropomorphic animal people, evolved and thrived in relative peace and harmony in this cradle of life.

Thousands of years ago, a small population of humans crash-landed here, accidentally (probably) killing the caretaker god Animothros. He fell to the ring's surface, creating an island with his skull. The humans lived and survived there, influenced by his magic-suffused corpse. They soon spread out and, with their great cleverness and ambition, as well as being helped to adapt by the Kin, came to dominate many areas, though they still mostly coexisted peacefully.

Nuvonia is a different story. It developed military and logistic technology that it used to oppress its neighbours, quickly sweeping most of its continent, and taking over Kastria, along with gaining its previously well-adapted technologies and engineering. Notably, the Kastrian takeover was largely bloodless, as they accomplished a palice coup of Kastria's elites. Kastria's various peoples, especially the Kin, fled in droves, though a client government rules in name, earning its members wealth and privilege.

Enigmas and Mysteries The final truth of the Soulstream isn't really known. To some people, souls are dissolved into it as a generic stuff; to others, souls remain more or less intact, so that reincarnation is of the distinctive personality. In general there is a wide variety of attitudes and theories on spirituality and sacredness.

There are relics of some old tech strewn over the world, limited to a maximum of “cassette futurism”, e.g. Start Wars-type tech.

No one has ever seen the Hub.

Nuvonia is pretty shitty to the Kin. This isn't really a threat that could topple a nation now, but it is a growing tension.

Some kind of rot is afflicting the vegetable basis of the world. This is bad, because it could let the air out. Someone should do something about that.

At the same time, Horos is fighting back with various “monsters” that do not distinguish between the rot and other things that aren't Horos infrastructural rhizomic stuff. So they are getting very aggressive about “cleaning up.” This is bad.

The humans here actually came from a different “terrarium world” of the Titans, fleeing persecution and environmental degradation there. They were the rich and privileged who could flee, though they were humbled soon enough. Luckily for those left behind, along with bitterly resenting the ones who could flee, they figured out how to survive: necromancy. Also they developed more advanced space flight. They know where their traitorous fellow humans went, and are interested to re-unite. Forcefully. A comet in the sky that comes ever nearer is actually this undead empire's braking burn on their capital ship. This is going to be a Very Big Problem.

The “fix-it” religion of the robot monks is schisming, with some fundamentalists taking a very puritanical conception of what's “wrong” with things. This schism seems to be sort of infectious.