Android soldiers of varying models and capabilities were produced just prior to the Fall to complement (and then replace) the armies of mankind. The variety of shapes, appearances, and sophistication of these ranged from post-Fall wonders of military development, to cheap buckets of rivets and steel mass-produced during the fading years of mankind’s brilliance on earth.
As man’s presence began to dwindle during his final wars, and his grasp on the surface world began to slip (often forcing him to underground retreats or domed fortresses where the radiation and diseases couldn’t reach him), he began to turn towards brain-wiping, preprogramming, and drafting older androids more and more to fight his battles. In the end, mankind vanished, leaving only scattered armies of artificially intelligent surrogates who, one by one, shut themselves down in the absence of a cause – only to revive themselves sometime in the far future.
That future, of course, is now.
Androids possess the uncanny ability of the human mind to plan and predict the unforeseen, and the super advanced calculation and processing ability of robots. On the battlefield they have no match, in man, mutant, or monster.