Stonehell is my pick for the best of the 21st century megadungeons (and is, I think, one of the first in the OSR mode). It’s in two parts, the initial Stonehell Dungeon: Down Night-Haunted Halls arriving as a self-published print on demand product in 2009, and the second part, Stonehell Dungeon: Into the Heart of Hell wrapping things up in 2015.

The dungeon began as a tyrant’s prison, where the prisoners were forced to excavate their own living space. The tyrant fell, but when the prison was liberated, not everyone left — lots of folks considered the horrible place their home. The top layers still retain their prison-like feel, and numerous former prison gangs have carved up the complex into small warring kingdoms. Deeper levels get stranger. At the very bottom is the lair of a creature of pure chaos that feeds on the negative emotional energy generated by the inhabitants. The more it eats, the more it destabilizes nearby reality. This goes a long way toward explaining why the place is so weird (there’s a casino down there somewhere, and at least one crashed space ship).

Dungeons are inherently irrational, and even though it is unlikely that a group will ever “solve” Stonehell, I feel that as a whole, it justifies its irrationality in a way few other dungeons of any size do, and this makes it feel unique and special. Its also extremely usable — despite being something like 1300 rooms, each level is made of quadrants that are detailed in a derivative of the One-Page Dungeon system, so everything is clear, brief and even modular — you can rearrange, drop or use any section on its own, should you wish. It’s really quite the accomplishment, especially considering it’s Michael Curtis’ first big outing into design. No wonder he became such a big wheel at Goodman Games!