As I’m pondering this megadungeon project, I’ve discovered there are several types of megadungeon. Or maybe “design approach” is a more accurate term than “type.” So here are the ones I’ve come across. I’m still deciding which one resonates the most, and/or which will be best for this endeavor.
The Mad Mage Deathtrap Approach
This is a very common approach to megadungeon design. The idea is that an enormously powerful wizard, having lost any sense of empathy or ethics, decides for some reason to build a giant underground complex filled with traps and monsters. And he/she/they decide to lure adventurers into this deathtrap dungeon, by also placing marvelous treasure in it. The wizard devises some mechanism or magical method for resetting traps and restocking monsters.
Undermountain in the Forgotten Realms is one of the better known megadungeons of this type. Particularly since Wizards of the Coast published Waterdeep: Dungeon of the Mad Mage in 2018. It’s probably the oldest megadungeon design approach, and many “old school” D&D/RPG aficianados favor this type of dungeon for that reason.
The Mythic Underworld
This is another way that old school D&D/RPG fans explain the huge, deep, often incongruous and nonsensical, perpetually resetting megadungeon. It is made into a mystical and mythological endeavor, and the mystery of how the dungeon resets, or how it keeps expanding, is a holy mystery not meant to be solved.
I love mythology and mysticism as much as the next literary nerd. But perhaps you can tell that this approach doesn’t really sit well with me. Honestly, I think I like the “mad mage” approach better than this packet of nonsense.
Gygaxian Naturalism (or The Ecology of Monsters)
This is the latter-day approach developed by Gary Gygax. There was an ecology to monsters. DMs were encouraged to figure out the food chain in the dungeon, to figure out which monsters would team up and which would fight each other. There were opposing factions in these megadungeons, that you could side with or set against one another. Dungeons also had an original purpose, but then were used by other beings until the builders were long turned to dust. Or become undead.
This is the approach most DMs and adventure designers use today (if they create large dungeons at all). However, given the size and depth of the true megadungeon (15-25 levels deep, each level sprawling and expansive) it seems to me that Gygaxian Naturalism might break down a bit. But I suppose you could have layers of ruins, mixed with natural caverns, and you could make this approach work. And perhaps the lowest levels have portals to the Underdark, or other worlds, or other planes.
The Living Dungeon
This is a concept I came across in the 13th Age RPG. The living dungeon is an actual living being–a mighty magical construct of some kind. It spends long stretches of time laying dormant beneath the ground, then breaks violently from the surface. It devours towns, cities, dungeons, ruins, incorporating some parts of them into itself and consuming the rest. The model, or prototype I suppose, of this concept is the Eyes of the Stone Thief adventure.
I admit this is the one I find most interesting. However I don’t think this would work well for the kind of open-table game I want to run. Because the living dungeon is a malevolent creature, the main objective is to enter it, survive, and make your way inward and downward until you find the creature’s heart. At least, that’s the objective in Eyes of the Stone Thief.
Choosing a Type
It’s looking like either the “mad mage” type or the Gygaxian Naturalism type is going to be most suited to the open-table format I’m going for. I do want to try out a “living dungeon” sometime, but that would be something for a stable, ongoing group that’s willing to try something a little different. So if we are going for the “old school” types, I guess the next thing to do is figure out which dungeon (or dungeons) I want to use.
So tune in next time, when I’ll start going through the copious amounts of dungeon adventures I’ve managed to collect. I’ll be doing 2-3 per post, I think. Stay tuned, Gentle Reader!
The Cool Mama 
Looking forward to hearing more. I’m starting a campaign of Dragon Heist, and thinking about what to do at its end, if we continue from there. DotMM doesn’t feel like it will go over well with my crew (too removed from the RP and city as written), but Undermountain as a living dungeon is a really interesting idea – especially because the threat it represents to the city could be made manifest pretty easily.
DotMM is a BIG honking dungeon. It’s remarkably large, even by megadungeon standards. There are folks in Adventurer’s League who went all the way through it…but I’m not sure how many people outside of AL have done that, or would want to. I see it more as a resource…plenty of stuff to steal! If you want to make it into a living dungeon though–that’s a fascinating idea. I recommend you take a look at Eyes of the Stone Thief. The full version is for 13th Age (you can get it at the Pelgrane Press site), but they released a kind of preview version (just the first two pieces) in a 5E compatible version (which you can get on DriveThruRPG). The full version is interesting because it’s really describing a collection of parts rather than a set of dungeon levels. It’s basically a kit, and you can mix and match, take things out and fit thing in however you want to. So if you are trying to make some other megadungeon into a living dungeon, that would be the prototype to follow. Good luck!
Nice – thanks! I will check it out.