Half breed idea
I was thinking of starting a role play with human/animal characters, in a fantasy, survival style world were one has to not only survive natural events thought out by me and others I assign, or simply just each others simple killer instincts in the world of prey and predator.
In this role play, the gods and goddesses (me and others, we can play normal characters as well) have decided they have had enough with humans and there destruction of the world, so they took every offspring the humans had and gave them animal features, to we're no science or medical knowleadge could change them back. After generations had passed, and the half breeds starting killing others, war sprung loose, the cities fell and the wild world took back over the areas.
300 years later, the old cities are now ruins and the human/animals flourish like normal animals with only the small social remenants and physical features of there long extinct ancestors.