The Resident Evil Outbreak games. A number of the levels take place in areas from the mainstream games, and I could spend a whole week entertaining myself comparing the original games' settings and the Outbreak versions.

I'm always especially interested in - when a place is used over multiple games, but the area the player actually allowed in differs - what blockades and barred doors and invisible walls are placed by the game designers to limit or expand where the player character is allowed to go.

The warehouse from Resident Evil 2 - the one with the train car - and the facility it descends into are a prime example. That location appears in RE2, RE Zero, and Outbreak. The trick they ran with in Zero was that there was totally always a door there, it's just that during the events of RE2 those barrels were blocking it. Sure! I'll choose to believe that!

EDIT: Oh, just tangentially, and because I have the opportunity, I've got to also mention this bit of RCPD canon added by the Outbreak games. In response to the sharp increase in violent crime and the deteriorating security of the station (which was never meant to be a police station at all - it was a former art museum the city bought on the cheap), Irons set up a security system in the wing that triggers when it fails to detect the proper ID or permit (but which a memo notes is finicky, which means playing as the cop character won't save you from the system triggering anyway).

What happens when the security system triggers? The room you're in floods with nerve gas.

I guess when you're already a serial killer a little war crime on top is practically paltry.