(Post zombie apocalypse)-a tribe of humans
Culture: Drumming circles daily around an arena for their bravest brutes to slaughter their accepted foe, the zombie. Feasts of overcooked zombie flesh (to kill all of the zombie virus present). Wooden fortress that make this tribe in the far future look several millennium behind in technology. Instead of becoming a troublesome and unnatural foe that they seek to cure, this tribe has accepted that Zombies will continue to roam their land and, if the undead were to perish (be cured), this tribe would suffer as well.
The party has found the source of the strange creatures roaming the countryside. The rift in this reality glows with a silver hue, rippling with the wind but never moving. They step through and are immediately assaulted with the scent of rotting meat, some have to muster all their strength not to vomit. Strange cries similar to the beasts the party had faced before can be heard in the distance. Looking around, they see they are in a forest of grey and red rather than the normal brown and green. The trees are sticky to the touch and writhe, perhaps to get away or perhaps as a warning.
The deeper the party goes, the more the forest seems to slither and move underfoot. The cries get closer and more numerous. Creatures lurk in the shadows, all the same color of their surroundings. Whatever the party came in here for, they had better do it fast.
The forest of flesh is waking up, and it is so very hungry.