This is Claymore’s tweaked spawning, he use more or less since A16. He was too lazy to make it a XPATH mod, but now decided, to finally get it done. Not too hard, because it’s simply a remove and append.
Wasteland is now harder and if you’re not prepared, at least the night in the cities probably give you headaches to survive. Also made it a bit more realistic. For example: At the day, animals and zombies can die, because it’s too hot. Same for snow, but here in the night, because it’s too cold. Overall it’s harder and more zombies than the vanilla will spawn. But also more animals, so food won’t be that of a problem.
The forum topic of the mod is here.