Unusual Megadungeons

[MrZJunior]

What sort of megadungeons can you make beyond the classic twelve or so floors of caverns and tunnels?

I was thinking you could have a giant fortress that stretches up a mountainside with multiple baileys. The first one could be an abandoned town. Next a ruined monastery. After that a horribly overgrown garden, and so on. Each level would be separated by the walls of the old fort, providing a similar effect to a traditional dungeon. There would be all sorts of sally ports, tunnels, and other such things connecting the levels to reduce linearity. You could fit in more complexity by connecting the main fortress to smaller outlying forts or towers, these would act as mini dungeons.

What other unconventional megadungeon styles can you think of?

[Man_Over_Game]

Each room is a separate object with portals. Each portal has a unique rune and several outbound runes you can select to choose where the portal leads. You have to gather up a knowledge base of where each rune goes and what each portal can lead to.

Randomly pressing buttons will still activate the portal, but cause a mild arcane explosion from it leading into a magical void, dealing a sort of arcane sickness to everyone nearby.

Many of the denizens are rather stupid, and maintained notes or ciphers to keep track of how to get to where. As a result, the players' ability to travel matches their ability to gather information and slay the inhabitants.

[Tvtyrant]

What sort of megadungeons can you make beyond the classic twelve or so floors of caverns and tunnels?

I was thinking you could have a giant fortress that stretches up a mountainside with multiple baileys. The first one could be an abandoned town. Next a ruined monastery. After that a horribly overgrown garden, and so on. Each level would be separated by the walls of the old fort, providing a similar effect to a traditional dungeon. There would be all sorts of sally ports, tunnels, and other such things connecting the levels to reduce linearity. You could fit in more complexity by connecting the main fortress to smaller outlying forts or towers, these would act as mini dungeons.

What other unconventional megadungeon styles can you think of?

Inside a giant, city sized animal is a classic trope that is still weird. Flipping it so it is a normal animal and you got "honey I shrunk the kids"sd would be weirder.

Really, really shrunk inside a tree so the cells are the rooms and the enemies are protists, amoebas and fungi.

Much less shrunk and you are stuck inside a fairly big mansion which has rooms the size of small countries, mammals are colossal beasts and cockroaches are huge.

[MrZJunior]

Each room is a separate object with portals. Each portal has a unique rune and several outbound runes you can select to choose where the portal leads. You have to gather up a knowledge base of where each rune goes and what each portal can lead to.

Randomly pressing buttons will still activate the portal, but cause a mild arcane explosion from it leading into a magical void, dealing a sort of arcane sickness to everyone nearby.

Many of the denizens are rather stupid, and maintained notes or ciphers to keep track of how to get to where. As a result, the players' ability to travel matches their ability to gather information and slay the inhabitants.

So a bunch of rooms connected by portals? Are the rooms like normal dungeon rooms or like separate mini dungeons in and of themselves?

[redwizard007]

OP made me think of the orcs attacking the White City in LOTR.

One could apply the same principles as OP with a massive fleet of ships. I picture something like the greco-persian conflict depicted in the second 300 movie, but could be applied to anything from catamarans to aircraft carrier.

Each ship is a "room," (or series of them.) Deck hatches, ladders, rigging & stairs allow access to the crows nest, hold, captain's cabin, rowing deck, quarterdeck, etc. Boarding ramps, loose rope, cargo nets, small boats, flight, jumping, and simple swimming can allow movement between ships.

[MrZJunior]

Inside a giant, city sized animal is a classic trope that is still weird. Flipping it so it is a normal animal and you got "honey I shrunk the kids"sd would be weirder.

Really, really shrunk inside a tree so the cells are the rooms and the enemies are protists, amoebas and fungi.

Much less shrunk and you are stuck inside a fairly big mansion which has rooms the size of small countries, mammals are colossal beasts and cockroaches are huge.

Oh man, shrinking. The thought would never have even occurred to me. Very cool idea, very creative.

[Agent-KI7KO]

I wanted to copy Etrian Odyssey and have a mega dungeon keep going up a huge hollow tree filled with monsters.

[Tvtyrant]

Oh man, shrinking. The thought would never have even occurred to me. Very cool idea, very creative.

My first major campaign I included a whole fraggle rock//hunger games part where an evil wizard shrank the party and threw them into a terrarium full of tiny warring tribes and animals. They had to escape through the terrarium's air mechanism, which was a dungeon made of moving metal parts.

Shrinking stuff opens up whole new worlds of possibilities.

[MrZJunior]

My first major campaign I included a whole fraggle rock//hunger games part where an evil wizard shrank the party and threw them into a terrarium full of tiny warring tribes and animals. They had to escape through the terrarium's air mechanism, which was a dungeon made of moving metal parts.

Shrinking stuff opens up whole new worlds of possibilities.

In a game I was playing in a party member received a potted miniature forest, including bonsai shambling mound, as a gift.

[Tvtyrant]

In a game I was playing in a party member received a potted miniature forest, including bonsai shambling mound, as a gift.

Just make sure it doesn't get struck by lightning!

Honestly though that sounds like the coolest quest reward ever.

[Man_Over_Game]

So a bunch of rooms connected by portals? Are the rooms like normal dungeon rooms or like separate mini dungeons in and of themselves?

I'd make it so that each room had an explicit design, something pristine that has been defiled by the new residents. Now, the concept itself is pretty bonkers, an entire dungeon consisting of assorted rooms located in random locations in a pocket dimension, so the reasoning behind each room doesn't have to make sense.

Consider the fact that the Wizard who'd create this dungeon would likely see each room as an individual broom closet. If you were trapped inside of your bedroom, and you knew that there was an empty void surrounding you and leaving you nowhere to go, you'd start to go a little batsh**. Either out of insanity or for some unknown purpose, some of the rooms just don't make much sense to normal people.

Maybe there's just a hallway with a portal on either side, just so that its creator had a reason to walk around without feeling claustrophobic. Or maybe he just felt that any proper dungeon has a long hallway. Or that both ends connect to ley lines that are integral for the dungeon's design Who knows?

[MrZJunior]

Just make sure it doesn't get struck by lightning!

Honestly though that sounds like the coolest quest reward ever.

It was from a game with a heavy emphasis on cooperative world building. I came up with it as a reward for a side quest related to my character.

I like these sorts of (seemingly) useless but flavorful items, much more interesting than yet another thing that makes you slightly better at doing other things. It gets really cool when people start coming up with creative and fun uses for them.

[Mordar]

My first major campaign I included a whole fraggle rock//hunger games part where an evil wizard shrank the party and threw them into a terrarium full of tiny warring tribes and animals. They had to escape through the terrarium's air mechanism, which was a dungeon made of moving metal parts.

Shrinking stuff opens up whole new worlds of possibilities.

Like the possibility of me singing..."Dr. Shrinker, Dr. Shrinker...he's a madman with an evil plan...".

Love the idea.

Another thought - an island adventure, focusing on moving up from the shore to the top of the formative volcano and taking advantage of the model/idea that there might be 8 (or 10, or 11) climate zones on that island. A themed mega adventure, more than dungeon, that allows you to incorporate wildly different adversaries while still making some kind of sense. I also recommend a trip to Maui or the "big island" Hawai'i for research purposes. But stay away from Kauai.

- M

[MrZJunior]

I also recommend a trip to Maui or the "big island" Hawai'i for research purposes. But stay away from Kauai.

- M

I like it. Do you know who's giving out grants for campaign related research these day?

[falcon1]

I like the idea of there being a megadungeon which is based off islands: there are several dozen islands with various structures, caverns, etc. with dangerous creatures in the water, narrow safe paths between the islands, and all sorts of groups both hostile and not.

[Imbalance]

Mega as a matter of perspective?

Rather than being shrunk, the party finds an ancient tomb or temple built by giants. There may only be a handful of rooms, but they're enormous and just exploring each space takes hours. Have one big enough for a dragon to take flight.

On the other end of the scale, the party is tasked to rescue an important sprite from an evil warlock. They learn that he has been trapped in a labyrinth designed especially to imprison his kind. None of the heroes may enter, but via scrying and message spells or even illusory magic they could possibly guide him to freedom. The warlock, realizing she can't stop them, sets traps and sends other tiny monsters into the maze. To the players, it's a bit like watching someone else play a video game, only they must collectively describe to the sprite which way to proceed to avoid danger and escape, whereas he can only see the dim tunnel before him and must decide whether to trust their directions - a trust that will erode each time they lead him into a trap or enemy.

He has no means of defense, but cannot be killed, per se, inside the maze. Each time he would come to harm, he takes exhaustion, until the point of death, which resets the whole prison and places him back at the starting point. When he encounters a monster, he flees in the opposite direction. To put a time clamp on matters, the warlock grows tired of your meddling and ultimately sends a pudding into the labyrinth that will eventually fill every path until all hope of escape is lost.

[RazorChain]

Floating city or a fortress comes to mind

[JAL_1138]

The Far Realm. (Or Limbo; it’d work just as well.) Conventional geometry does not apply. Going around a corner and then turning back to go the way you just came might instead lead you down an entirely new path. Nothing makes sense, and there’s no consistent theme. You might walk down a columned hallway in a stone temple and find yourself standing in one of the many mouths of a deranged Old One speaking gibberish blasphemies. There might be areas with no gravity. You might have to roll a saving throw to avoid falling in and getting lost in an impossible angle if you stray too close to the corners.

[Tvtyrant]

Sunken pirate ship counts for sure, 2qy cooler then the normal dungeon and obviously full of sea monsters and money.

An old classic is the fallen space ship, if you use Spelljammer it would be fantasy but there was an old module with laser gun toting mindflayers. Maximum meta: fallen space dwarf fortress full of space orcs and a space balrog.

[Particle_Man]

Underwater dungeons allow for more three dimensional combats and the like. Plus coral is pretty.

[Wraith]

Inside a giant, city sized animal is a classic trope that is still weird. Flipping it so it is a normal animal and you got "honey I shrunk the kids"sd would be weirder.

Bonus points if the creature that you are exploring is one of the players' characters, who is also there via some kind of projection/minor simulacrum spell.
Functionally it wouldn't make a difference but it could up the stakes if, every time someone hurls a careless fireball at an enemy, their friend takes a tiny bit of damage or other related affect - blinded or dazed for a few seconds. Or maybe something even more exotic, like an errant spell suddenly causes them to grow a tail or something, if you'd prefer the tone of the game to be more comedic than tragic

[Seto]

I'm working on an megadungeon (well, a big dungeon, but adventure-sized, not campaign-sized) that's 5 dungeons rolled into one. At its core, it's a large temple to Nature and the Elements. Large, but not "mega". The trick is that the "normal", visible temple in the Material Plane is mostly empty corridors and halls, with blocked passageways and a secret inaccessible central sanctuary. But different versions of the temple simultaneously exist in the Planes of Air, Earth, Fire and Water. They're accessible from the Material plane temple. Same layout in every case, although one version could have an open passageway whereas the others will have it blocked - but those are not empty: they have guardians, enchantments, traps... To make gradual progress through the base temple, you need to go do stuff and unlock secrets in the elemental ones. It will probably require a lot of back-and-forth between the same rooms in different dimensions, but should be rewarding to the players when they see progress. Only by mastering every version of the temple can they access the central room.

Sort of a Legend of Zelda dungeon, I guess.

[Thorongil]

Much less shrunk and you are stuck inside a fairly big mansion which has rooms the size of small countries, mammals are colossal beasts and cockroaches are huge.

I’m running my players through something similar this week.

The giants in my setting were upwards of 100 feet tall, and they left behind castles to match their size when they departed eons ago for this setting’s version of the Uttermost West.
So scaling a staircase is like climbing a mountain, the castles are crawling with giant rats, cats, birds and insects, simple low-level warding spells and traps do massive damage, to say nothing of the kenku flocks that guard the giant library.

I highly recommend trying this out.

[The Glyphstone]

Maybe you could do some ancient, abandoned city that is like a multi-level Venice except that there is no water. So, you have a huge mess of pathways, bridges, and platforms that the PCs explore. It could make for some interesting combats too (being on different platforms of varying levels, jumping between them, and trying to push monsters off.

Sounds like Sharn in Ebberon.

[Wraith]

If you're feeling brave, sadistic and/or otherwise just enjoy squeezing your brain into unusual shapes, there's also SolkaTursilver's Hypercube Trap, which is basically a horrible dungeon all of it's own.

[Brother Oni]

There's the dungeon from Dungeon Meshi, which repairs itself and each floor is essentially its own ecosystem, so one floor might have an artificial sun which supports forest animals, dryads, etc, while another level is a massive lake, complete with deep sea megafauna.
It's rumoured that the original creator/ruler is still around and is responsible for the dungeon's lower levels re-organising their layout on a semi regular basis.


The dungeon in The Tower of Druaga was a massive vertical tower that extended up miles and was probably a mile or two in circumference. The regular loot gotten out of the dungeon supported an entire town outside the dungeon and the tower had been so explored that there were outpost towns higher up in the tower, that could be used as a base of operations for dungeon crawls.

Like Dungeon Meshi, each floor was large enough to support its own environments, with desert, snow, etc levels. They're not as detailed as in Dungeon Meshi, but the magic of the tower keeps replenishing the monsters.

[Flumphburger]

For an elemental themed dungeon that doesn't just do the elemental portals thing...

A dormant volcano.

You have the fire levels around the still-hot magma tubes. The ice levels near the apex, maybe including some parts that are full on ice caves carved or melted into the frozen crater lake nestled into the top. You have the water levels near-ish to the fire ones, where snowmelt has flooded some of the caves and is of highly variable temperature depending on how far you are from the magma. This snowmelt, along with magmal activity, is probably what ate all these labyrinthine caves into the mountain over the ages. Wind levels are when you have to cross the exposed mountainside for a ways. You could have green/forest/etc levels by putting some patches of forestion the more sheltered crevices and ravines of the mountainside, with multiple cave mouths and overland paths leading to and from each. And of course, earth is everywhere.

Throw in a ruined dwarf city, a cave system near the bottom that used to be connected to the underdark and still has underdark ecosystem in it, a town of azers or efreeti (still occupied, or long abandoned) built atop the magma pool itself, etc.

[Tvtyrant]

There is also time as a concept to play with. Rooms could be at different times from each other, or the dungeon is moving through time much faster then the players so doors rot away and cave ins happen randomly and frequently, changing the dungeon as you walk across it. Caverns can rapidly fill with water then empty out, entrances fill behind you and stalagmites grow down like spike traps to stab party members.

[The Kool]

I discovered an interesting element recently that caused a dungeon which fit onto a single sheet of graph paper to be about ten hours of play, and little of that was combat. Your dungeon will feel a LOT bigger if the edges wrap around (a hallway that leads off the edge of the map on one side connects on the other side) and is fairly labyrinthine. Players will feel overwhelmed by the number of potential passages to take, and the dungeon will feel far bigger than it is until they start retracing their steps and realizing that things look familiar. My dungeon was 25x25 squares. The effect compounds as the size increases. For added layers of disorientation, include hallways that don't feel like portals but jump from one section of the map to another. Play into the limited input the players are getting, and let them figure it out on their own. It will be highly rewarding when it all comes together. Bonus: This type of dungeon works extremely well with traps of all sorts.

[DuctTapeKatar]

If you want to be REALLY mean, just copy the White Palace from Hollow Knight and adapt it into a tabletop RPG, Path of Pain included. But in all seriousness, that place is literally inside of a dream, so that's a pretty neat place to have a dungeon of that sort.

An idea that I had shared for a worldbuilding project on this site is actually a castle hanging from the roof of a cave, above a pit of toxic gasses.

Though it might not count as a megadungeon, the cave itself is a dungeon on its own, with platforming challenges and beasties hiding in the rocks. The castle itself is an abandoned dwarven citadel hanging upside down -- the interior is trapped, probably has undead or something worse hanging around, some of its towers and rooms reach into the gases below, and to make matters worse is that the building is incredibly old and it shows, with some of the passages breaking apart completely and plummeting into the cavern below.



I had thoughts about a mostly-aquatic dungeon made from crystalline towers above a vast ocean of still water, with various water-slides and such between the pillars of this domain to assist in movement between them -- but the largest issue of this place is that I'm not sure what to do with it. It sounds very pretty from an aesthetic standpoint, and could have some really interesting puzzles, but in the end, I'm not sure how to work out the lore of this place. You have towers of white gemstone, neat, and they stand atop what is basically a lake, and it is also a water park, but WHY is it made out of gemstone, why is it on a lake, and who decided that the best way to get from one tower to another is via water slide?