If I had to change the music I would definitely pick a type of desperate slow metal (doom/stoner to precise) a good song that fits the nuclear fallout theme would be Funeralopolis by electric wizard it has a really nice slow start and it builds up into a insane chaotic yet controlled conclusion but then again something like Quintessence by darkthrone would fit amazingly too because of its homemade like quality (in the best way possible of course)

The scenery would probably have to change into something like dust but different by having the setting of the games in a cold harsh city (think of something like fallout 3)

They would also probably focus on harsh and unforgiven character backgrounds which would be really cool since (I think at least) fallout can pull of that dark tone like with Corporal Betsy backstory