That's an outstanding game, clearly a huge amount of work. Well done and thanks for sharing.
I agree some more dirt and rubble will really add to the effect - I would suggest your terrain cloth would benefit from a scatter of dirt/rocks scenic material all around the buildings (if that isn't too much cleaning up for afterwards). The book also mentions cacti, trees and other foliage, so you might want to up the vegetation slightly.
Anyway, thanks again, a real visual treat.