All His Angels Are Starving is outstanding in that regard, this one's both on Scribble and RR, especially the very freaking end of book one. Damn.
Necroepilogos, also on both sites, it's a kind of postapocalyptic horror. Delivers a fairly typical postapocalyptic mix of machine, human, and everything in between, but does it in an unusual (at least compared to most stories I've read) and often very disturbing ways.
Other stories from the same author, primarily Katalepsis, also fit the bill.
Also, Nowhere Stars matches to some degree, but it's not exactly a horror.
If you're interested in manga, I'll also give two:
Urasekai Picnic, though it's far more grounded than most stories. I think I read the manga at MangaDex, not sure where you can find the novel it was based on.
Another on the same site: One Day, Suddenly, Seoul Is. It delves more into human interactions later on but at least the beginning is great.