Games with optional 100+ floor dungeons?
Lufia 2's Ancient Cave, Beyond Oasis Flame Sword dungeon, FFXIV's Deep Dungeons, I think one of BotW's DLC's was one... I'm a sucker for this mechanic, and I'm sure there's plenty I can't recall and dozen's that I've never seen.
Roguelike's don't count, has to be an optional part of the game, not the core loop.