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D&D General Megadungeons

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Yes. I don't do it often because I find it can get pretty tiresome, but I have done 300 location dungeons which is plenty large enough to carry a party over three levels.

What do you want to know?


Victoria Rules
I was just curious if it was actually possible to do, and what kind of dungeons you created if it was.
It's possible, but kind of under the heading of "anything's possible given enough time and effort".

Designing a megadungeon is a crap-ton of work; much of which can probably be saved by picking up one of the various published megadungeons that are out there (a few examples are Ruins of Undermountain (a 2e boxed set), the three combined parts of Rappan Athuk (3rd-party 3e); and Temple of Elemental Evil (late 1e/early 2e book)) and then just modifying what's there to suit what you want.

The dungeons I design tend to be around 30-50 locations, not through any real pre-planning but more because that's just how big they happen to end up once everything's in there that I want. On a few occasions I've tried designing something bigger, and more or less quickly abandoned the idea when my patience ran out. :)


I created a living dungeon that was growing from a seed of Creation. The seed was a nascent consciousness that dreamt monsters into being, because it needed sentient minds in order to grow to fruition and fulfill its purpose.

Each level had a different theme.

One was filled with weird goblin mutants.

Another was a friendly village that worshipped the eye in the cavern ceiling above them, but they would transform into vicious monsters when the eye closed (and would remember none of it the next day).

The deeper levels were each a fully realized demiplane. There was one where centaurs were tormented by a pair of evil dragons (there was a good dragon hiding on that plane, but she stood no chance against the pair of them).

This was a few years back, so I don't recall every level. They eventually made it to the bottom and discovered the seed, which asked them to help it in shaping a new world.

The dungeon wasn't the whole campaign though. It was a wholly optional side-area that they'd make forrays into when not undertaking other adventures.

One strong suggestion I'd recommend for a megadungeon is to include shortcuts that allow the party to skip levels. Retreading old areas can be fun (especially if you make changes, to reflect the "living" state of the dungeon), but too much of that can undercut progress after a few levels.

Apart from that, I've heard that Dungeon of the Mad Mage is a fairly decent megadungeon.


I was just curious if it was actually possible to do, and what kind of dungeons you created if it was.

So, pretty much anything is possible, but my advice would be to plan something diverse enough that it is not going to get dull and repetitive and which is going to provide different sorts of challenges to face.

There are actually a lot of threads on EnWorld about megadungeon creation techiques that I've participated in over the years. I'll see if I can dig them up.

However, for those that say megadungeon creation is a ton of work, honestly the megadungeon/delve/haven format is the least labor intensive homebrew campaign you can run. Urban adventures for example tend to be much more work to do well, because large cities are much more complex than any megadungeon that doesn't itself contain a city. I'm not saying it isn't a bunch of work, but it's a lot easier to focus all of your creation on a dungeon than it is a world or a region. The biggest problem with it is that you often have to do a lot of work up front, but once you've done that work you don't need to do a lot of prep between sessions.


5e Rappun Athuk is about as mega as they come. I mean...huge.

Dungeon of the Mad Mage/Undermountain is very good as well. Not as grim, more tricks than traps.

Both kind of suffer lack of detail in places (due to their sheer size I suspect) but easy enough to fill in. Undermountain is also very easy to expand, doubly so if you have the two boxed sets.

Creating your own can be fun too. I rely quite a bit on random generator tables for everything from layout to contents. The 5e DMG has some great tools to do this - best since the 1e DMG (and in some places better IMO).


Goblin Queen (She/Her/Hers)
Has anyone ever created a megadungeon before, like a place where the characters enter the dungeon at level 10 and come out level 13?
10 to 13 hardly seems like what I would describe as a *mega*dungeon. A big dungeon for sure, but when I think of megadungeons, I think like Undermountain, Castle Greyhawk, or the Tomb of Elemental Evil. Stuff that you could spend a whole campaign exploring and still not have seen all there is too see.
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Rappun Athuk grew out of the tradition of every DM having their own dungeon.

When I started playing in the mid 70's players would come over to my place and explore my dungeon. Then, a couple of days later we would migrate to another friend's place and explore his dungeon. We would use the same PCs and sometimes there would be large disparities between character's power and level.

These games were huge by modern standards - typically 12-15 players - we used a caller during exploration. I wish I had some of those old dungeons, but they were pretty nonsensical and lacked much in the area of "dungeon ecology."

During the winter months it was common to play three or four times a week. The game was pretty new and we loved it - playing revolved around memorable encounters and was much less about 'story.'

It was a great time, but it would not be a satisfying game experience for me these days.

The trick with megadungeons today is to provide interesting encounters, in a dungeon ecology, with a theme. For the most part, my players, (who love combat), eventually tire of just killing stuff and stealing their loot.
Each level had a different theme.
So, pretty much anything is possible, but my advice would be to plan something diverse enough that it is not going to get dull and repetitive and which is going to provide different sorts of challenges to face.
I will just echo these posters' recommendations.

My group is finishing up Dungeon of the Mad Mage and we have had a blast. However, the dungeon is very explicit about having a theme for each level. It's made for a very enjoyable campaign.

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