Sci-fi Dystopian underworld trash heap survival/horror/suspense?
I never got to finish this book, I was 16 (around 2014) or so when I started reading it. I just remember it was insanely good. I don’t remember much either, i believe the main character fell down a manhole or somehow fell below the streets, and there was tons of garbage and whatnot. The last chapter i remember reading up to I believe there were magical fungus that may have tried to communicate with him, and there were some kind of large shadowy dangerous mutant creatures he had to watch out for. He would scavenge a lot and try to make things out of garbage, trying to find his way to the surface while also trying to solve the mystery of why the underworld existed.
I’m sorry it’s so vague, my stepdad pirated the book for my kindle and I was in highschool when I started reading it. The book comes to haunt my memory every so often and now that I’ve got back into reading I’d love to finish it.
I just remember: man falls below into garbage/toxic waste heap, mutant creatures, fear and suspense, a battery pack maybe? And something hunting him. And mushrooms/something trying to telepathically communicate with him/lure him in. Thanks in advance.