Darkhive is a concept that's been rattling around in my brain for a while.
A mysterious ancient construct of an alien race, perhaps a prison ship adrift in the hyperspatial/astral realms. Various alien races end up stranded here, facing nightmarish beings and strange fused cultures made up from the descendants of formerly stranded explorers.
When I started writing the notes for this setting, here's what I wrote...
(This is pretty "stream of consciousness" stuff... I'll clarify it over the posts in the next few weeks).
At the centre of darkhive lies a dying star. In a distant part of the universe, the darkhive might be described as a dyson sphere, perhaps even a series of concentric dyson spheres. It is a relic from a bygone era, a decaying monstrosity of cracked crystal and corroded metal, infested with fungal growth and mutated vermin. Scattered throughout the darkhive are gatherings of scavengers and drifters, living in shanty towns hidden in the less degraded parts of the hive. These survivors are descendants of various group of mystical explorers, astral warriors, and warp-riddled psychics who came to the darkhive unaware that they might never leave this shattered hulk. Constant passive threats to the survivors come in the form of inadequate food and water supplies, spore diseases from the fungal growths riddling the hive, and insidious mutation that festers within the body, erupting into savage transformations if left untreated. Active threats to these survivors come in the form of the insectoid creatures known only as the Shellbrood, the biomechanical Hiveguards remaining from ancient times, and the most savage degenerated mutants who lingered too long in the least stable parts of the hive.
There's more to it, but things always start small.