-Akira Jones, Tech Shaman of the Prometheans
As we always knew it would be the fall of humankind was one of our own making, although not in the way any of us predicted.
It happened in an instant. The collective unconscious, the shared imagination of all humankind, cracked open like a dam and fantasy flooded reality. The boundaries between imaginary and real came tumbling down. Volcanoes gave birth to dragons, and the monsters under the bed were made flesh. Fictional towns appeared from nowhere, populated with people who had decades worth of memories. The symbols of humankind's greatest ambitions and the fevered nightmares of it's most monstrous abberations came to life all at once. All of human myth and fiction, all the gods and monsters spawned by the human imagination over the millenia of our existence came crawling from our minds and into the real world.
Humans themselves were not immune from the effects of the Fall. Some people mutated into their bizarre self-images, becoming fox-people, magical hermaphrodites, demons and things stranger still. Those who remained human were killed by the billions as humanity entered an age of chaos and anarchy the likes of which had not been known since the stone age. Humans were hunted by fantastic new predators from the darkest recesses of their unconscious fears. Almost quaint by comparison, mass starvation in the early days of the Second Dark Age claimed hundreds of millions.
None know for sure exactly how long the Fall itself lasted, that period of seemingly impossible anarchy during which the fundamental laws of reality were suspended. Eventually these laws reasserted themselves, but not before the world was rendered almost unrecognizable.
When the laws of physics returned, those things that absolutely could not exist died, leaving behind only their impossible corpses. Those things that merely had not existed stayed, however, and many interbred with the more stable natural creatures. Even worse, some impossible things continued to exist in spite of themselves, finding their own bizarre niches. Earth would never be the same.