Echidna

A combat robot, designed to destroy any interdimensional threat, yet due to some malfunction, did not activate before The Fall of Humanity. If activated, is capable of annihilating the Demons enslaving Humanity, but has a module that was not intended to ever be used. This module will cause Echidna to desire to rule Humanity. When this module was installed, Echidna was made into a fully-functioning Futanari, enabling her to create a better Humanity. This, combined with the personality module means that, even if the Demons are defeated, Echidna will try to conquer Humanity to create what she believes to be the next step of Human evolution.

In the year 3089, scientists across the globe detected bizarre fluctuations at the poles. Upon further analysis these turned out to be some kind of portal from another dimension. Fearing the worst, a countermeasure was prepared. Project Echidna sought to create an army of robots capable of fighting the interdimensional threat, however as the project progressed only one unit was manufactured. With Humanity's hopes put into one robot, the world stood still as they waited for the portals to do anything. Then, in the year 3234, the portals opened and not just at the poles, but globally. Within minutes all governments were felled, what few survivors were either enslaved or forced to run and hide. Demons now ruled the Earth with an iron grip, it would not be long until the last few free Humans were captured or killed. You are one such survivor and you find yourself inside some old laboratory, the computers that still work have documents labelled "Project Echidna".