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?
I like how terraria and minecraft mix premade blocks with procedurally generated terrain, also Spelunky has interesting level generation, they even had a talk about it.