Obsidian Twilight: Is it this or that or even that...

While looking at trailers for Left 4 Dead (god I love that game), I had to wonder; is Obsidian Twilight a post apocalyptic fantasy setting with zombies OR is it a zombie apocalypse in a Fantasy setting OR is it a Dying Earth subgenre setting with undead? Let me hear what you think and why. Talk to you later...