Horizon Zero Dawn: 10 Things A Prequel/Sequel Must Address
8. Operation: Enduring Victory
The operation was a lie - there was no chance for the human race to survive. But still, wouldn't it be interesting to see all of humanity involved in a futile fight to save itself, while the scientists worked on GAIA and its subordinate functions?
The end result would be known, expected, but the emotional load of fighting machines, believing that one is saving the human race only to find that there's no chance of survival later on in the game would be definitely something worth exploring.
Learning that the supposed super weapons program was a smoke-screen to force people into fighting would make for a touching moment.
Tying into the previous point, this point in the timeline would be the perfect place to explaine the "apocalyptic glitch" (called that way by Elisabeth Sobeck) that caused the robots to malfunction.