pds41: - Bioshock (2007) - it's showing it's age slightly now, but the tricks the devs used to make Rapture seem believable (and the decision to use art deco stylings, which are low on detail but look fantastic) mean that it still holds up today
- Dishonored (2012) - almost looks like a painting. A bit grey, but works for the atmosphere of the game
The jump in fidelity between 2000 and 2005 vs 2015 and 2020 is an interesting one. I think part of it is the fact that you've gone from very few polygons to a low, but considerably high number. So, the fidelity looks a lot better, but it's still quite basic.
2015 to 2020, you've gone from loads of polygons on the screen to loads and loads - probably a bigger jump in raw numbers, but less visible to the naked eye (things already looked quite good). Plus, developers have got a lot better at hiding rough edges and shortcuts taken to make things look good. That, and the fact that with an insane amount of HDD space available vs 15 years ago, anyone can stick high definition textures on stuff these days.
Excellent point about storage space being a factor as well as raw horsepower.
Bioshock and Dishonored are two of my favorite games simply for the worlds themselves. Art direction and how it paired with storytelling made everything feel alive and engrossing in a way that no amount of graphical fidelity would have managed on its own.