That's the coolest part of this game, basically being a part of the fall of a dystopian world.
So are the enemies roaming free through the levels? Or are they static and tied to a location?
From what I've seen its mostly static placement but I don't think you would notice much unless you replayed sequences multiple times. It's not open world though, there are sections where you can explore but for the most part its a linear experience.
Playing: XCOM 2, Diablo 3 Watching: American Crime, Regression