In the 17th century an anonymous alchemist predicted that in the future the earth would be invaded by an alien civilization and that humanity, in its distraction by greed and lust, would be devastated without difficulty. So he built some models of automaton robots with materials and components he knew, some far ahead of his time but which he had access because of his knowledge of the secret sciences. And, blending technology and magic, hid and programmed them to just wake up when humanity was on the verge of extinction, to fight the invaders and restore life on earth.
He called this group of robots the Metal Legacy Project and left him an inheritance so that future generations could be saved from a tragic end. But, unfortunately, when the robots awoke there were fewer humans left in the world than expected and almost nothing of the other shapes of life.
Now, with the world almost dominated by the invaders, the mechanical warriors of the Metal Legacy Project wage a war for the restoration of the planet and the possibility of the resurgence of human civilization.