Just a collection of grimy/decayed building interiors, generic horror stuff really.
Playing around with the foggy/mystical atmosphere. What I like about fog in general is how it obscures and mystifies what you can see ahead of you, and gives it a ghostly aura.
Looking into the eeriness of a cold winter setting, I think the bottom left and bottom/top right best capture what I was thinking of. Fog plays into these two, but I was focusing on the night setting too.
Went a bit far-fetched and looked at alien hives. They're inherently scary, for a number of reasons. The idea was an alternative to the over-grown setting of our idea, since it essentially keeps the same atmosphere of the humid, organic building, but is completely out of place in it's own right.
And finally, I remembered about the Eden Project and the idea of "biomes". This was an alternate idea to the hive, with a similar atmosphere. Here, you'd have quite blinding flood lights and a thick dense mist, as well as spores and fireflies floating around. The trouble with this idea is that it doesn't scream "horror", and it'd involve a lot of vegetation.
Just some mental noodlin', trying to get inspiration for visual styles and colour palletes.