Elden Ring has the deepest, most complex worldbuilding of any game ever made, and it’s not even close. For anyone interested in worldbuilding I strongly urge you to watch some Elden Ring lore videos from The Tarnished Archaeologist to learn about the techniques that the Elden Ring devs use to put incredibly deep and subtle worldbuilding into their games. It’s changed the way I think about worldbuilding in any context.
As a young nerd obsessed with RPGs and William Gibson’s work I was outraged at the idea of putting fantasy into cyberpunk. But then I picked up a damaged copy of the Shadowrun rules from a bargain bin and was blown away by the worldbuilding, they really found a way to make it all fit thematically and logically and I ended up running the game for years.