From the introduction:
Rex Pyrenees wiped blood from his muzzle and adjusted his grip on his sword. He looked around for his attacker, but all he could see was the forest around him, surrounded by the ominous black bark of the trees. The only sign of the demon was its laugh, a sinister chuckle that whispered around him with the wind.
...
Imagine our planet, but far in the future. Countless centuries have gone by, and everything looks very different than it does now. Most building have crumbled to dust, and broken roads are buried deep beneath dense forests and plentiful flora. Here and there, the occasional ancient ruin or incomprehensible object surfaces, giving tantalizing glimpses of a world that once was. The work of mankind is slowly reclaimed by nature, but there are no humans. Mankind is gone, living on only in its collective works. And those that have been left behind decide to reclaim the world.