The demons arrived from beyond the gate to take over the world, starting a long war against a united human army. A war that humanity had no chance of winning.
Gunpowder and bullets had no effect on the demons who used their magic to obliterate all who stood in their way, leaving humanity helpless until the augment technology was invented.
A bastardization of science and the greatest breakthrough in human history, the augmented soldiers were the greatest warrior humanity ever produced. Capable of controlling the powers of gravity itself, they were equals to the demons in power and gave humanity a chance at victory.
These are the memories of one augmented human who came back to life only to find that the war was lost, and that his world was ruled by demons.