Hephaestus ' reason for creating human killing machines in Horizon Zero Dawn is undisclosed .
Aloy returns to the Banuk Shrine , where CYAN has transferred herself to , and CYAN provides additional information about the Old World but warns that HEPHAESTUS is still active somewhere , and will continue to build machines designed specifically to kill humans , which is why it tried to seize control of CYAN and its facilities .
Horizon Zero Dawn