I don't know if you played "Pixel Dungeon", a roguelike game, 25 floors in 5 stages, very silimar...

Well, Dungeon Crawl have 5 stages (Bricks, cobberstone, stone bricks, mussy stone bricks and nether bricks [or obsidian if nether option is disabled])...

I think if this could have certain probabilities to make it more interesant:
5th floor could have 60% to generate in nether bricks (or variants), 30% to generate in blackstone (or variants), and 10% to generate in obsidian blocks.
Maybe if a 20% of all towers have 6th floor, a "End theme", with more treasures, more overpower mobs and more endermans
6th floor could have 80% (16% really) to generate end and obsidian blocks, and 20% (4% really) to generate obsidian and purpur blocks and shulkers too.
Maybe 10% all dungeons have double size (yeah twice fun), or 10% all dungeons are lineal, or 10% have more house rooms.
A hallway with lava or some pressure plates (some with tnt, other without tnt) could be brutal, or a room with tramps and a great treasure.
I heard someone want a final boss (vanilla we have Wither, Warden and Ender Dragon), maybe "Mowzie Mob's" could work to generate a Ferrous Wroughtnaut, Frostmaw or Barako, the Sun Chief; maybe 30% could have a boss.

This could custom by config file.
Great work, I like your mod from 1.16.5