For me it was encapsulated by doom 3 for the most part. Games with strong dynamic shadows like splinter cell chaos theory and stalker with a mix of shiny specular effects is timeless for me. When I go back to these games the shadows still feel as good as they did when they came out and the lighting perfectly crafting the mood. A lot of modern games now even though their fidelity on paper is much better just always feel extremely flat to me and don't pop out of the screen like they used to. It seems like they're missing contrast and UE5 seems to make this even worse where all the games using it just look like mush
Late Amiga 3D games. You could just tell the vision far exceeded the hardware's capabilities, but that didn't stop them from trying. Some really impressive technical tricks and code optimization in that era because you couldn't just throw more hardware at the problem.