It is the far far future.
Civilisation spans stars and universes, nestling sparkles of light and warmth among the vast inhospitable infinities of unexplored and uninhabitable space. Throughout the universe, rare habitable worlds groan under the weight of teeming billions.
This vast interstellar civilisation depends on stabilised exotic matter both for parapsace FTL and maximal efficiency of realspace reactionless drives, the psychotronic devices of aetherspace, and the magical, mythic, and mystic artifacts of mythospace and bardospace.
Rarest and most precious and potent of all are the godlike, immensely long-lived yet still mortal, celestials, whose bodies precipitate down through the zones to realspace, where they are mined for the priceless god-ores.
Rather than being the masters of the galaxy, humanity is just a middling race existing under the feet of more powerful godlike beings. All these middling races scavenge, trade, and war with each other, build teeming cities and avoiding the heel of the monstrous and godlike beings above them.
Space travel is a matter of every day occurrence for those fortunate enough to be born into, inherit, or gain occupation in the spacer lifestyle. The rest make do as best they can in the palaces and the slums of the cities, or struggle against hardships to establish new colony worlds, or join hopeless crusades against rival middling species for worlds and resources.
But civilisation expanding, requiring more and more exotic matter. And the more exotic matter that is used, the greater the paradox buildup.
As the cosmic balance is increasingly disturbed, survival requires locating the greatest celestial of all. But that means journeying beyond known spacetime, to uncharted regions where madness beckons yet anything is possible.
Celestials – godlike, immensely long-lived, yet still mortal, entities who reside in mythospace and above. Interstellar civilisation is built on the bodies of celestials, religions are initiated by them.
Cosmology – the cosmos consists of a number of zones or gradations, each of which is characterised by specific laws, and characterised by particular phenomena. The higher through the zones one translates, the more plasticity that is required, but also the easier and further one can travel.
Drones – these are machines or biobots with only limited autonomy and intelligence, although more independent than a remote bot. They are used in many roles, both civilian and military, as, unlike sapient robots and AI, they are unlikely to rebel.
Economics – while many economic systems are used, it is corporate capitalism that has been most potent in spreading across the universe. Here madverts, monomaniacal sentient advertisements, serve as important tools of memetic subversion, causing shoppers to buy their commodities
Habitats – habitats may be terraformed planets (or very rare garden worlds), enclosed biospheres on inhospitable worlds, moons or asteroids, or orbitals, space stations, or even worldships,
Politics and Empires – there are many contending empires, based on morphotype, ideology, and purpose, co-existing, forming alliances, jockeying for power, conquering, exploiting, or liberating.
Races – likewise there are many different races of sentient, sapient, and transapient beings, including AI, aliens, cyborgs, humans, hyperdimensionals, mechanoids, posthumans, splices, and more. Each category consists of innumerable subtypes and combinations.
Tech organic or mechanical, nano or megascale, tech is what makes interstellar civilisation go round.
Ships – These are classified according to function, composition, plasticity, zone, etc.
Weapons – while there are chemical, bio, nano, and nuclear wmds, and even exotic paradox weapons, as well as memetic (propaganda) warfare, and various nonlethal devices, most weapons used in battles still tend to be either kinetic or beam in nature.