K'almarck

The dead do not die. Not forever. No creature knows what woke them -- but there are infesting things, in the light, in the dark. They chitter and growl and purr and twist their morphing-flesh into the bodies of victims, rending apart tendon, popping sinew, bursting eyes. A corpse, every corpse, is stolen. Remade. Weapons in hand, the stretched and broken body is posssessed, altered, joins the mindless horde. The denizens, wherever they live on K'almarck, are fighters against the most inexorable tide of all.

Geography

Several continents on K'almarck -

a tropical continent in the north, lush with greenery and jungles, the most advanced tech civilization on the planet lives here; most everywhere else is somewhere in the iron age while this is the group that figured out how to communicate with the "Visitors" from above

a continent divided into three parts by a mountain range; a massive desert in the middle of the mountain valley that appears unlivable but is one of the safest places on the planet because the creatures that steal the flesh and blood and body cannot live long in the blistering heat

southern continent where a "viking" adjacent culture has a series of cultures. one of these groups has managed to actually build a crypt, and the whole group has a strange view on death where the dead -- the ones who are not taken by Rotting -- are dismembered, stripped of flesh and meat, and then thrown into a crypt because that is the way they can be honored and buried. their skin and their flesh is used to continue on the life of the rest of the clan.

Ecosystem

A vicious and strange ecosystem in which the sapients on the planet are constantly targeted by a strangely aggressive life form which all but ignores those life forms which are not sapient. These horrid creatures charge right past animals with no regard for them at all.