On the rpg front, I've been re-reading some of the Dark Heresy plot ideas, in particular the Curse of Solomon.
CoS, as a story idea, is set on the Hive World of Solomon. Solomon is in the later stages of a Hive World's lifecycle, which is to say it's a shithole. Natural resources stripped, everything polluted, mutation growing ever more problematic and the inevitable death of the world looming over it's inhabitants.
The 'curse' is an entity, force or phenomenon referred to as the Beast, which preys upon the citizens living in the lightless wasteland of ruins and pipes that covers most of the planet's surface. The locals fear it, sacrificing outsiders, their own and even imperial officials to it in the hopes of staving off their own deaths, chaining their victims to the pipe network in remote places of their community and leaving them to the dark. It strikes only in the absence of light, so the inhabitants cling desperately to the light of promethium fueled lanterns to try and avoid it.
The Inquisition has several theories as to what the Beast is, most dismissing it as nothing more than local superstition created to cope with the oppressive suffering inherent to the area, some thinking it a cult or criminal syndicate preying on the locals, the actions of a piece of lost and foul technology that strikes at random, a monstrous xenos predator, or just an accident of the planet's own nature.
I've been thinking about what I would choose to be the Beast of Solomon, and I'm leaning towards the xenos predator angle, but with the twist that it's not there of it's own volition nor a natural inhabitant of Solomon. The Beast is the lead actor in a twisted black market video holo franchise, the syndicate uses augmetics implanted in the beast, and servo-skulls and cyber-animals to record it's hunts and kills, and then sells the images and holo vids, shed fangs and scraps of the victim's remains to the perverse and sadistic elements of the Imperium.
Of course the fear, the despair, the horror. Perhaps a more unnatural element has been drawn to the perversity? It's the sort of thing where I could take months to settle on a Beast I truly like.