What is it? I don’t really know. Oxford calls it “a genre of fiction that encompasses works in which the setting is other than the real world, involving supernatural, futuristic, or other imagined elements.” How does it differ from fantasy? Bookriot has an interesting post discussing it, along with quotes form Atwood and LeGuin. Call it ‘weird,’ or perhaps, There’s an overlap with urban fantasy, but generally no werewolves. There’s also an overlap with apocalypse and dystopia, but since I have those in a separate index, most won’t be duplicated here.
Lexicon by Max Barry
Pandemonium by Daryl Gregory (and most of his work)
Only Forward by Michael Marshall Smith (and most of his work)
The Seep by Chandra Porter
Cursed by Jeremy C. Shipp
Annihilation by Jeff Vandermeer