Procedural generation is an interesting topic to me, as it forgoes traditional level design in favor of a bunch of formulas, rules, and random elements to make varied replayable gameplay.
One of my favorite procgen games is Dwarf Fortress, and how it creates a fully realized world with lore and history, and then places both fortress and adventures as relatively small stories in said world.
Also Deep rock galactic is great in varying its caves, from normal tunnels to massive caverns that you can only traverse using ziplines and platforms
Any other interesting procgen games?
Returnal is not fully procedural, it’s lego like procedural.(rooms types are limited, but the layout is procedural.)
Riftbreaker(RTS-ish with a player controlled mecha) procedural generate the location and missions so the resource type distribution roughly matches how much you “expand” your area of control. (ie the more you expand outward, the more rare resource patches starts to show up.)
Many rougelike/lite use procedural generated levels.