Node-Based Megadungeon Design

A better landing page for this series, including links to related materials on other blogs, can be found at KJD-IMC: Node-Based Megadungeon.

— kjd

I’ve spoken before about scenario design that focuses on the relationships between various elements of the scenario before the physical layout.  These techniques can be used to manage the relationships between various adventures, and within a single adventure or dungeon, but I didn’t really go into how it can be used to manage a megadungeon.

I have seen ‘megadungeon guidelines’ that suggest laying out the various levels and regions, then populating them.  This has some merit, but there’s a step that can be done before this that really helps: mapping out the contents of the megadungeon, the inhabitants and their relationships, before scribbling even the start of the map.

I took a few minutes this morning and came up with the following list of potential regions for a megadungeon (updated to provide links to the specific regions as they get developed):

  • The Abandoned Tower: Abandoned, broken-down wizard’s tower.
  • Wolf Den: A large wolf pack bent on mayhem and domination of weaker creatures.
  • Goblin Warren: Desperate goblin clan looking for a way to escape their erstwhile ‘allies’.
  • Fungoid Cavern: Overgrown region of fungus, slimes, oozes, and other non-plant vegetation.
  • Dwarven Safehold: Military base staffed by professional soldiers.  Not a lot of amenities, but dwarves don’t need them.
  • Clockwork Hell: Mechanical madhouse, with lots of inexplicable machinery (and servitor automatons to protect and repair it).  I am suddenly reminded somewhat of Castle Heterodyne from Girl Genius, and of the ‘advanced civilization’ areas of recent Zelda games.
  • Aristothanes’ Sanctum: Sanctum of an eccentric wizard who wants to know “how everything works”, and is prepared to disassemble anything needed to figure this out.
  • Pit of the Misshapen: Civilization, such as it is, of broken creatures.
  • Fane of Baalshamoth: Alien source of knowledge, though the price is often misunderstood.
  • Aboleth Conclave Outpost: A sink of depravity and treachery, where those in power oppress their subordinates while appearing to work together until active betrayal becomes a viable path to power.
  • Shalthazard the Pale: Spectral wyrm so consumed by lust for knowledge and manipulation he did not notice his own death.

Generally dangerous, with a couple places that could be relatively safe.  Note that the region names are pretty generic, for the purpose of conversation.  In practice I would name at least the Mad Wizard and the Dark God, and probably the dwarves of the Safehold, the Abandoned Tower, and probably the goblin tribe.  The information paths (or adventure hooks, if you prefer) would similarly be more specific.

I then identified relationships between the various elements and laid them out (GraphViz is a wonderful free tool for this), resulting in the map below.

Megadungeon Map
Megadungeon Map

There eleven distinct areas within the megadungeon (I don’t count ‘Outside’, it’s mostly an anchor for the diagram to show easy entrance points… but I’ll come back to that) with numerous links between them and notes about each link.

This makes it pretty easy to see how the various elements interact, and a bit of cleverness in laying it out even comes close to how it might look on the actual map.  I can build on this to develop each region, showing detail in a similar manner.  I would develop each of those graphs separately; there just isn’t room to do it here without cluttering things hopelessly.

It seems I’m mistaken.  When I finished outlining the megadungeon I ended up generating a graph of all nodes in the dungeon, breaking each region down into smaller areas.  Take a look at the graph here to see how it turned out.

Information Paths

This graph can still be built on, though.  As the various subgraphs (levels and regions) are developed, at a similar high-level view, further informational or “clue” relationships can be identified.  For instance, notice that the Fungoid Cavern is a travel hub — as long as you aren’t dangerous to them it’s a relatively neutral area you can pass through (no inherent animosity, and it connects to many things). If you talk with the dwarves, you are likely to find that they know quite a bit about what is going on in the dungeon.  In addition to their immediate neighbors, some among them might know about the following:

  • Clockwork Hell: someone clever but perhaps bent built this. Some wonderful craftwork, shame it doesn’t work properly.  We have been studying it for a while.
  • Pit of the Misshapen: the Fungoid Cavern is visited by some twisted, pitiable creatures…
  • Mad Wizard’s Sanctum: … created by mad bugger of a wizard that we sometimes see lurking around the edges of the Clockwork Hell.
  • Abandoned Tower: the safest, or at least least-contested, way to the surface.  Could probably make our way through the Goblin Den but it would likely be a fight; probably not worth it unless we have to.

They might well know more than this, but it’s a start.  Similarly, the Misshapen might be able to tell of:

  • Goblin Den: small ugly men that are mean.
  • Dwarven Safehold: small gruff men that are gentle.
  • Abandoned Tower: if you go past the Fungoid Cavern you can find a place where the air is dry and it’s not always dark.

Clockwork Hell might have no one to actually talk to, so it may not have any such links.  Even so it is possible that there could be:

  • Dwarven Safehold: Signs of dwarven exploration and examination, possibly a team is even here.
  • Goblin Den: less likely to find any here at any given time — it’s dangerous and doesn’t offer much — but it’s possible, and there could be other evidence they have visited.
  • Dark God’s Altar: perhaps the Altar was what broke the person who built the Clockwork Hell, or the powers of the Altar have directly affected the Clockwork.  The Mad Wizard might not even have been here originally, he came sometime later and ‘inserted himself’ between the two (and continues to explore the Clockwork Hell looking for more stuff he can use).

Showing the information paths between just these three nodes might look like the diagram below.

Megadungeon Information Paths
Megadungeon Information Paths

(I’m mildly annoyed; I know I have run GraphViz in a way that new edges don’t change node placement, they work around it, but I can’t find now how to do that.  Green lines added using Paint.Net.)

The green lines show the information paths described above.  I may or may not include them, or just the really key ones, because they tend to clutter things a bit.

Ingress and Egress

Just as the individual nodes (levels and regions) above contain their own subnodes (not shown, but discussed above, the detail of each region) that point to the other nodes in this graph (and possibly their subnodes…), it is obvious that this map could be extended to have links to and from other maps outside the megadungeon.  I started to draw them, but again it complicates things.  However, I can easily see the following paths in and out of this map:

Physical Paths

  • Dwarven City to the Dwarven Safehold (the Safehold was placed here specifically to monitor the aboleths).
  • Shalthazard’s lair to the Underdark (he presumably doesn’t stay here all the time, but doesn’t particularly need a path to the surface — he goes and hangs out in the tunnels and caves deep underground… I wonder what he’s looking for).
  • Aboleth Conclave to the Undersea, or possibly a river above washes misadventurous types down here — they didn’t die, It Got Worse).
  • Local village is having trouble with Goblin Raiders.

Information Paths

  • There is a cave of wondrous beings that can be traded with to gain various fungoid materials, including drugs, poisons, and healing materials.
  • The wizard Aristothanes reported a strange mechanical structure underground and has gone to examine it.  His reports became less and less frequent, and now we haven’t heard from him in a couple of years.
  • The wizard Aristothanes is believed to know the spell you are seeking.  If you can find him, he may be willing to trade with you.
  • The item you seek was last known to be given to Shalthazard the Pale in tribute; if you can meet him forcefully enough he may be willing to deal with you.
  • You want a spear enchanted against aberrations?  The Safehold Dwarves know how, you might try them.
  • Our village is being watched by goblins, I’m sure they are preparing to attack us!
  • There is a lost Altar of the Dark God somewhere under the Abandoned Tower.
  • Exploring the Altar of the Dark God, you find a prophecy of His return, and the stars are almost right!
  • The Aristothenes has uncovered forbidden lore (which is what drove him mad, of course) and has horrific plans.
  • Shalthazard is the mastermind behind the recent upheavals.  You defeated him here, but he escaped and likely plans revenge on you.  (Or you killed him and now have in your hands the reins of an immense network of agents… what do you do with it?)
  • After you survived being washed underground by the river, you managed to escape the aboleths and found safety in the Dwarven Safehold… and they have something they need you to do back in their city.

Closing Comments

I’ve spent a couple hours on this this morning, mostly describing what I’m doing and why.  In practice, and with supporting information from my campaign (this is completely from a cold start) this could take somewhat less than an hour.  There is a fair bit more fleshing out to do, but I’ve got an outline I can easily look at and understand and use for further development.  When it comes to exploring this, I know enough about each region that I could easily prepare a region in an hour or two (using similar techniques) for use for a couple of sessions, at least, and that the PCs are likely to return to.  I hardly need to spend time on Shalthazard, for example, for quite a while, when the party is still dealing with the goblins.

This technique is just a specific application of my Campaign and Scenario Design techniques, and it fits in well with them.  It offers a way to quickly outline a megadungeon, with lots of material to use in outlining the specific regions, before delving into the actual detail used in play.  It provides an easy way to integrate other material.  For instance, ‘Clockwork Hell’ might be a particular module I’ve bought, and it’s now pretty easy to massage to fit, or I might pull out a generic “Dark God’s Altar” I’ve prepared before and reskin it (similarly with the Goblin Den and the Dwarven Safehold).

You have multiple paths through the dungeon (three ways in from the surface, plus lots of physical paths from there).  If you were hunting Shalthazard the Pale, you not only have lots of ways you could get there (non-linear dungeon, yay!), you can get enough information to make the decisions sensibly (player agency, yay!).

I can also, as described, expand on this to provide clues to things outside the megadungeon leading both in and out.  You might be looking for Shalthazard and discover the Dark God’s Altar, along with the prophecy, and drop those plans.  This is, in my mind, totally cool.  I might not have gotten around to developing Shalthazard beyond a name and general characteristics, so I haven’t lost a lot of time, and he may still be there when you return.  Or, because I know about him and you smashed his holy place, he might send his agents looking for you — any work I have done to this point isn’t wasted.

Finally, because of the non-linear relationship between the regions, and my knowing the relationships but not how they will be explored, I get to be surprised by how things turn out, and in a great way.


  1. Just recently started doing this with my wilderness maps, with time-distances labelled between the various points. Not as pretty as some of the Cartographers’ Guild maps, but quicker to make with all the necessary info. Will be posting an example on my blog as soon as it’s safe (once players have been let loose on it).

  2. Now I am wondering about a tool that can take a topographical description like this, a bunch of geomorphs (maybe with tagging and/or seed tiles to ensure theming: e.g. the Altar region should really contain an altar somewhere), and generate the dungeon layout for me.

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