Dungeon Design: Megadungeon Design

Designing a megadungeon is hard. If you don’t get the dungeon’s metaphorical foundations right, you are wasting your time.

By William McAusland (Outland Arts)
By William McAusland (Outland Arts)


Over the last forty years, countless dungeons and hundreds of megadungeons have graced GM’s campaigns all over the world. Detailing such a locale is a gigantic undertaking.

When designing a megadungeon, keep in mind the following criteria:

Layout & Design

  • Name: The megadungeon should have a cool, flavoursome name.
  • Multiple Entrances: There should be several different ways of getting into the dungeon. While all might not be obvious (secret entrances are cool) most should be easy to find by all but the most blinkered explorer. Entrances set in the midpoint of the dungeon provide access to dungeon levels both above and below the entranceway.
  • The deeper you go, the more dangerous it is and the greater the rewards. This is a tradition of dungeon design. However, it is better restated as the further from the main entrance you go, the greater the danger and greater the rewards. Some dungeons may go up not down or could run for miles and miles at roughly the same depth.
  • Each level (or sub-level) has a distinctive flavour. This flavour shouldn’t be unnecessarily odd just for the sake of flavour. For example, a sub-level of twisted natural passageways home to degenerate and feral derro seeking a way down to a deeper level is an example of good flavour. A level dominated by a mad alchemist who has no connection or relevance to the greater dungeon is bad flavour.
  • Sub-Levels: Smaller, self-contained areas, sub-levels enable the GM to inject different kinds of flavour or monsters into the dungeon. Sub-levels may only be accessible from one normal dungeon level. Some may be secret while others may provide a relatively safe haven for explorers.
  • There should be multiple connections between levels and sub-levels. The PCs should have freedom of choice to decide which parts of the megadungeon they explore. Access points between levels often serve as choke points. The more access points there are, the easier it is for dungeon denizens to move about and the more choices the players have. Some connections should be hidden or secret. Not all should proceed only to the next level; some may provide access to multiple levels or may miss one or two levels out (for example a connection might exist between levels 1 and 4).
  • Secret & Remarkable Connections: Not all connections between levels and sublevels should be a standard staircase. A dried up well shaft, flooded passage or chasm are all good examples of other connections.
  • Players should have meaningful choices: This doesn’t mean the party get to choose which door to use to get to the villain’s throne room. Rather, the complex’s layout enables the PCs to pursue multiple paths through the dungeon, exploring different areas, sub-levels and levels as they choose. Wherever possible, the PCs should enjoy freedom of movement through the dungeon and not be forced down a set path.
  • Links to the deepest dungeon of all. The megadungeon should have one or more links to the Ebon Realm. This link provides tremendous design freedom to include strange, ancient monsters crawling up from the lightless depths in search of prey. It essentially answers loads of tricky questions about how and why certain monsters came to be in the dungeon.
  • It should all make sense (to a certain extent). Realism is good to a certain extent, but realism for realism’s sake is pointless. Worrying about the minutia of dungeon design is time spent not crafting exciting encounters and flavoursome dungeon levels and encounters. Enough information should be present for a GM to answer most basic questions about the dungeon, and no more. For example, deciding where the dungeon’s denizens get their drinking water is important. Worrying about the minutia of the dungeon food chain is not.
  • Minor Elevation Shifts: Dungeon levels should rarely be flat. Minor shifts in elevation can confuse explorers. Are they on the same level or are they not?
  • Extra-Dimensional Spaces: Used sparingly, extra-dimensional spaces provide an interesting change of pace to exploration.
  • Level Size: The dungeon levels should be of various sizes. Not all should fit on a single piece of graph paper. Some especially large levels may use a larger scale per square.

History & Minutia

  • Details, details, details. But not too many details. Empty rooms are boring. Standard corridors are boring. Dungeon dressing is an excellent cure for boring areas. Are the flagstones broken and cracked? Does dried blood splatter the wall in an otherwise empty room? Such details build verisimilitude and give the feeling the dungeon is a live setting.
  • The megadungeon needs a decent reason for existing. The megadungeon must have or have had a reason to exist. Did an ancient race use it as their lair, or did a wizard retreat underground to continue his strange (and undoubtedly dangerous) research? Whatever the reason, it will have left its mark on the dungeon’s layout, architecture and style.
  • There should be secrets to uncover. Be it secret doors, lost treasures or shocking discoveries about the dungeon itself, the complex should have secrets. The PCs should be able to uncover these as a result of good, attentive play.
  • Relevant and discoverable back story: The dungeon must have a relevant and discoverable back story. The greatest back story in the world is pointless if the PCs never get to interact with, discover and understand it. Knowledge of the dungeon’s history shouldn’t be automatic – they should have to work for it. Having knowledge of some or all of the complex’s history should provide insights into the dungeon (and perhaps even in-game advantages).

Denizens & Challenge

  • Wheels within wheels: The megadungeon should have an overall boss or super villain. This individual doesn’t need to be in charge of everyone in the dungeon, but he should be the most powerful and influential figure therein. He will have many sub-leaders or vassals; many of these will command their own level or sub-level.
  • Away with the 15-minute adventuring day. If every room contains a life or death struggle in which one or more PCs end up unconscious or dead the dungeon turns into an unending grind. The PCs do a room or two and then retreat to rest. That’s boring game play. Instead, the dungeon’s design should promote long-term delving. Parties should be able to explore at least a dozen rooms before resting. Easier fights, unoccupied rooms and easily if dealt with properly battles are all excellent tools to prolong the adventuring day.
  • Wandering Monsters: Monsters don’t just sit in their chambers waiting to be slaughtered. Some move about – either because they are scavengers or because they have things to do. Random encounters adds both an extra level of uncertainty to exploration and to the realistic feel of the place.


  • Settlements: One or more settlements should lie within relatively easy reach of the dungeon. This provides explorers somewhere to retreat to between forays. Here they can rest, recruit help, buy and sell magic items, gather information and so on.

Help Fellow Gamers

Do you have any other dungeon design tips related to this topic? If you do, please leave them in the comments below and help your fellow GMs design better dungeons today!

This article is part of Dungeon Design Fortnight. Dungeon Design Fortnight celebrates Raging Swan Press’s upcoming release of GM’s Miscellany Dungeon Dressing – a huge 336-page tome dedicated to all aspects of dungeon design and dressing. This article, along with loads of other useful information, appears in the book. I’m insanely proud of GM’s Miscellany Dungeon Dressing and I hope if you are thinking about designing dungeons you check it out.


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Creighton is the publisher at Raging Swan Press and the designer of the award winning adventure Madness at Gardmore Abbey. He has designed many critically acclaimed modules such as Retribution and Shadowed Keep on the Borderlands and worked with Wizards of the Coast, Paizo, Expeditious Retreat Press, Rite Publishing and Kobold Press.

16 thoughts on “Dungeon Design: Megadungeon Design”

  1. Great stuff, if I may add a few thoughts.
    1# Wondering monsters: I try to create what I call limited wondering monster lists based on local populations. This also means that when a wondering monster is killed its taken off the list and it might also be taken off a room description to.
    2#Vermin: I like keeping track of rooms where the party leaves the dead, this always draws vermin and can create a room where the vermin can be more dangerous than the original room inhabitants.
    3# Distance: To curb the 15 minute work day I like my dungeon to be away from human inhabitation, thus a wilderness hunted by the creatures in the dungeon awaits the party who thinks that the area is safe. Some pretty nasty things can crawl out and feed on the party.
    4# Starvation: I love the fact that the characters can starve and I let them.
    5# EXP: I found out the hard way that the 3.5 exp system did not work well with the idea of exploring a mega dungeon. I now use way points and objectives that award a package of exp, not for killing monsters, unless there boss like but for doing things that heroes can do.

    Great work guys

    1. #2 is a great idea! (I’ve also tried #4 but my players are irritatingly good at finding food – although they do often forget to provide their PCs with basic equipment.)


  2. Hi there, I am Benoist Poiré, co-founder with Ernest Gary Gygax Jr. of GP Adventures LLC.

    Your blog post was an enjoyable read. Thank you.

    I wrote my own megadungeon building advice which you can find here on the OD&D Discussion board: http://odd74.proboards.com/thread/7539/advice-build-megadungeon-setting-campaign

    Ernest and I are working right now on the publication of the Hobby Shop Dungeon, the megadungeon that has been explored by TSR alumni, customers of the Dungeon hobby shop and visitors of various conventions in and around the Lake Geneva area since 1978. Since neither Blackmoor nor Greyhawk ever made it into print in their original formats, the Hobby Shop Dungeon will be the first of the original megadungeons to be published in its entirety.

    The website is here: http://www.gp-adventures.com

    The facebook page there: https://www.facebook.com/hobbyshopdungeon

    We have a group too for those who want to talk dungeon design, the Hobby Shop Dungeon, and games in general here: https://www.facebook.com/groups/hobbyshopdungeon

    I just thought it would be important to let everyone know GP Adventures exists, what we are doing in respect to the subject matter of this blog post, and also let people know about the advice I posted some time ago about it.

    Thank you, and keep up the good work!

    Benoist Poiré
    Founder, GP Adventures LLC.

  3. Great list, and lots of very valid points that I’ve seen quite a few GMs, even some major publishers, miss out on when creating their own mega-dungeons. If there was one thing I could add onto the list of hints and tips regarding the narrative and physical descriptions of creating a mega-dungeon, it would be this: an Emotionally Conveyable Atmosphere.

    There is a reason (or many) why people avoid dungeons, especially mega-dungeons, at all cost. Well… the non-explorers and adventurers anyway. These reasons, sometimes even personal experiences with the dungeon, can and will bring up reactionary emotions in NPCs when asked about it. What they’ve heard, experienced, seen, done, and any number of interactions with said dungeon have left an impact on them, negatively most of the time thanks to a dungeon’s connotations and personal perils. It takes a really brave, really stupid, or really desperate person to delve into a mega-dungeon, let alone one that could be considered “normal.” The atmosphere of a mega-dungeon should represent and even magnify the fears of those who tell their tales to the adventuring party, and should be seen and experienced by the part themselves once they begin their delving into it’s depths. Perhaps some townsfolk out doing some prospecting inside one of the dungeon’s many entrances claimed to see the walls slither and bleed as if the dungeon itself was a living thing. This could turn out to be more true than the party realizes, as the entire dungeon really is a giant, fleshy, living organism that has grown around and inside the dungeon’s original infrastructure, or it could be the world’s largest living mimic!

    One such “mega-dungeon” (if you could really call a science fiction setting’s encounter a dungeon) I wanted to try and recreate for my Dark Heresy campaign was the Red Vaults of Luggnum, located within Luggnum Hive. I currently don’t have the book in front of me, but here’s the information as best as I can remember offhand. It was kept hidden away secretly from the planetary and inquisitorial authorities by a mad heretic known as The Red lady, under the guise of a noble called Lady Grey. The Red Vaults were used as her personal fighting pits and sacrificial chambers in dedication to the chaos deity Khorne, the lord of war, blood and skulls. She would occasionally kidnap large portions of the hive populace to be thrown into the vast, seemingly unending labyrinth to be hunted down and slaughtered by specially made murder servitors bound with khornate daemons and charnel spirits. Eventually she was found out by the inquisition and an order was sent to the local Adeptus Arbites (think of them as a mix of Judge Dredd and planetary police force) to begin a massed raid on the vaults and capture the heretic. Lore wise it ended in a mass slaughter of the arbites and the heretic managed to get away. I was going to make a mini campaign centered around a small party of arbites and those who worked along side them in their precinct who were part of the massed raid and now have to survive the horrors of the vaults.

    1. I’ve been thinking for ages about starting my own megadungeon, which is why I thought long and hard about how to actually design one.

      Today, I’ve started! If you hit the Gloamhold link at the top of the page you can my take on a megadungeon. I suspect I’ll be designing it for months if not years so come over and see how I’m doing!

  4. The megadungeon needs a decent reason for existing… Relevant and discoverable back story…

    YES- thank you!

  5. Dungeon Magazine #18 has a great dungeon in it – Tallows Deep. In fact the entire magazine is a great tool for getting players from 1-12 level.

  6. I don’t see why a megadungeon should have ONE supervillian. Competing factions withing the dungeon can lead to many interesting adventures.

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