World 13 was a highly dangerous area that ought to be completely avoided at any cost. At some point, humans in this world did something really stupid, which went completely haywire and ended with everything hitting the metaphorical fan. The lifeforms that didn't die had to mutate rather hurriedly, as well as turn rather nasty in order to survive.
It might be the result of a complete nuclear catastrophy, but this is sheer speculation based on testimonials of the demon hunters who have been there very briefly. Since neither of them has even the foggiest idea of what radiation is or how it works and no one who does know seems interested in braving monsters and possible radiation to find out...
This is the kind of place
not even especially not demons want to visit.
- After The End
- And Man Grew Proud No one is exactly sure what caused this world to turn out so disturbing, but as far as anyone knows humans were the only sapient species before it went boom it's assumed that somehow humanity mucked up.
- Dark World Well, the brave soldiers who spent all of five minutes there was a bit preoccupied with not dying and didn't take notice if it was dark for any other reason than natural dusk.
- Death World
- The End Of The World As We Know It
- Forbidden Zone Very strictly forbidden, and for good reason. It's not locked though, which might seem curious until you ponder that it's a mighty neat sectret execution method to simply kick someone through a portal to world 13 and never have to think about them again.
- Garden Of Evil
- Humanitys Wake
- It Is Beyond Saving Far, far, far beyond saving. Saving it implies staying there for more than a few minutes at a time. And surviving.
- Mutants Possibly. They do not appear to be humanoid or sapient, though admittedly there have been few attempts to make contact.
- Place Worse Than Death
- Thirteen Is Unlucky While there is some debate over whether 13 truly is unlucky or not, the ISM decided that since it was at least a somewhat significant number (a prime number) it would suit well enough for a world you really son't want to go to.