Megadungeon Thoughts

My “every day” goal is struggling (shame on me for starting a goal like this two weeks before the first GenCon we’ve had to prep for in 3 years…).

Over the last few weeks, I’ve been reading a lot of megadungeons, as I set my self a goal to write and map out my own dream megadungeon by the end of the year. It’s interesting to see both the evolution of the megadungeon, as well as the defining of what it means to be a megadungeon as the decades move on.

So I’ve been trying to design my own megadungeon rules to guide me as I work to develop this megadungeon. Here are the some of the guiding thoughts I’ve had on it as I’ve read a ridiculous amount of megadungeons (I really need to get to Arden Vul, as I’m very interested in that one. I need to snag it at some point.)

These are obviously what works for me and how I view it, not absolutes that I expect everyone should follow.

A Reason

Why is there even a megadungeon? For me, that’s the first question I have to answer. The core idea of a megadungeon is an unusual prospect in many settings. Why does this massive structure (in whatever form) exist? Why hasn’t it already been plumbed, explored, and mapped?

Internal Consistency

In my eyes, a megadungeon has to follow an internal set of consistency. A reason should exist for the megadungeon to be present, and it should have an internal logic to it’s presentation. That doesn’t mean it can’t be weird or fantastic, but it needs to have some underlying foundation that guides the presentation and design.


The inhabitants of the megadungeon should fit the theme, be placed at a reasonable point in perspective to the other inhabitants (No rooms that contain mortal foes next to each other.)

Nothing is worse than opening a door and being confused why something is inside it!


To me, a megadungeon should feel like a locale distinct, separate, and antithetical to the default world. It should feel like a place out of time, another realm populated by strange and unusual beings you’d normally not meet.


In my eyes, a megadungeon should be a living, evolving, and everchanging entity. Inhabitants should make alterations, move in and move out, expand or contract. Adventurers might impact it and cause changes, as can environmental or natural phenomenon. Any megadungeon should have guidepoints where the GM can show how it changes over time and exploration.

Things I don’t think megadungeons need

  • A “boss”
  • To follow the same physical/mystical/etc. rules as the real world.
  • Multiple levels (though I think it’d have to be a pretty large linear complex to qualify in my eyes)
  • The same sorta inhabitants throughout (although this can matter).

What do you think defines a megadungeon?