The Word in the Dark

Set in a post-apocalyptic, modern world, the protagonist is a survivor of a zombie virus outbreak and all out climate collapse.
Having been alone too long, he starts exhibiting signs of ill effects to his own psyche. Go along for the ride and explore the deep inner workings of one human mind as it tries to sort out what is real and what is fantasy when left to its own devices.
Flesh eating zombies, sub-zero temperatures, and total darkness might not be the only thing to fear when you are all alone.