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A megadungeon is both a campaign structure and a sort of exceptionally large and complex dungeon that a party may explore as part of a campaign using that structure. Large dungeons may be called megadungeons regardless of whether they are used in a megadungeon-style campaign.

The earliest ever campaigns of modern tabletop role-playing games used the megadungeon campaign structure, with Gary Gygax and other early GMs of Dungeons & Dragons running players through megadungeons like Castle Greyhawk.[1] However, no example megadungeons were published in the early days of the hobby and (for that and other reasons) they fell out of favour with most game groups. Megadungeons are still used and published, but are now the exception rather than the norm.[2]

Megadungeons in the game world[]

In Philotomy's Musings, Jason Cone associates megadungeons with the concept of an underworld, which he describes as "a place where the normal laws of reality may not apply, and may be bent, warped, or broken. Not merely an underground site or a lair, not sane, the underworld gnaws on the physical world like some chaotic cancer."[3]

He lists nine common characteristics of (underworld) megadungeons in the game world, as follows:

  1. It's big, and has many levels; in fact, it may be endless
  2. It follows its own ecological and physical rules
  3. It is not static; the inhabitants and even the layout may grow or change over time
  4. It is not linear; there are many possible paths and interconnections
  5. There are many ways to move up and down through the levels
  6. Its purpose is mysterious or shrouded in legend
  7. It's inimical to those exploring it
  8. Deeper or farther levels are more dangerous
  9. It's a (the?) central feature of the campaign[3]

Campaign structure[]

In a campaign with a megadungeon structure, player characters will alternately explore the megadungeon and recuperate in a safe space. Partly because their actions will affect the contents and inhabitants of the megadungeon (e.g. killing monsters that block their way, solving puzzles or disarming traps), and partly because they will become more powerful, the party will be able to venture deeper and explore new areas every time they return to the dungeon. However, the dungeon may also change for other reasons when the player characters aren't involved (e.g. passages change, monsters move around, traps are laid or reset), meaning that every venture into a megadungeon is filled with new experiences and surprises.

Safe areas are often relatively easy to reach by backtracking, being either immediately outside the megadungeon or even within the megadungeon itself.[4] This makes megadungeon campaigns suitable for episodic play, since player characters can return to safety at the end of each episode or session, and they therefore can be appropriate for open table play (i.e. with a variable group of players each session).

Story is largely driven by the players and the interactions of their characters, rather than through a plot prepared by the GM,[4] although some megadungeons (such as Monte Cook's The Banewarrens) can have an overarching plot as well.[2] Players can set their own challenge (and potential reward) by choosing how deep in the megadungeon to delve.[1] It can also be common to interact with monstrous creatures like they are regular non-player characters, as they may be the only characters to talk to in the depths of a megadungeons, and it may be the best way to deal with them.[4]

Good practice for megadungeons[]

Justin Alexander says that an effective megadungeon has three components:

  1. A jaquayed map
  2. A starting map key to establish memorable locations within the megadungeon
  3. Multiple random encounter tables for wandering monsters.[5]

It is useful to include multiple factions of monsters or other NPCs for PCs to interact with.[2][4]

Megadungeons can also avoid monotony by including areas of the megadungeons based on unique and interesting themes. Each themed area can include different puzzles, monsters and aesthetics, e.g. a fungus garden might feature myconids whereas a crypt might feature skeletons.[2]


  1. 1.0 1.1 DMDavid (2020-06-30). "When Megadungeons Rules Dungeons & Dragons". DMDavid. Retrieved 2020-08-12.
  2. 2.0 2.1 2.2 2.3 DMDavid (2020-07-14). "5 Reasons Most D&D Players Stopped Exploring Megadungeons". DMDavid. Retrieved 2020-08-12.
  3. 3.0 3.1 Jason Cone (2007). Philotomy's Musings, pp.22-24. Retrieved 2020-08-12.
  4. 4.0 4.1 4.2 4.3 James Haeck (2018-11-19). "What the Heck is a Megadungeon?". D&D Beyond. Retrieved 2020-08-12.
  5. Justin Alexander (2011-01-19). "(Re-)Running the Megadungeon". The Alexandrian. Retrieved 2020-08-12.

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