Horizon Zero Dawn: 10 Things A Prequel/Sequel Must Address
5. The Birth Of Religion
While we might read about the roots of modern religions, we are most often dealing with interpretations rather than facts, unable to get to the essence, simply because the events that laid the foundations for the stories that we use to define ourselves and our humanity happened a long time ago, and are not well documented.
The new part of the game could show how religion is actually born. By the end of the first part we learn that it was all a lie, and people were just worshipping another machine, but how did it actually come to this? What made people that left ELEUTHIA think something supernatural was involved in the creation of themselves, and the world surrounding them?
It probably didn't have anything to do with the names of Greek gods bared by GAIA herself and her subordinate functions, but maybe that's a good place to start?