Building a megadungeon: Level design

Level 3 of the dungeon, featuring 3 panopticon prisons, and dwarven halls to the south.

Once the history is established, you can set about designing the levels. 

First, create the levels according to the original purpose of the dungeon. Is it a mine? A prison for malcontents? A refuge? A storage site for powerful magics? A vault? 

Purpose drives design. 

Once you have that, you can start laying out the rooms. A prison will need areas for guards, prisoners, latrines, kitchens, waste disposal, barracks, bureaucrats, and so on. 

You'll need to plot out things like ingress/egress points. For a megadungeon, you'll want a number of them. If the original purpose wouldn't have many entry points, add new ones created by subsequent inhabitants, like goblins, kobolds, or purple worms. All of them dig tunnels. Xorn might follow ore streaks. Umber hulks might make tunnels following the same, and in so doing connect different areas and create new exits. 

Airflow is also important. Druidun has multiple airshafts going to the surface. Hot air rises, so at the bottom of these shafts are Dwarven Firestones, red hot slabs that cause the air to rise. Shafts may be split into two sides, one heated and one cooled, to generate airflow. 

The dwarves also have many Skystones (which draw in air from the plane of air), and Skygates (gateways into the upper atmosphere, which suck air into the dungeon).

Dwarven Runecarvers will bring in air and water elementals to manage air and water flows within their complexes. Earth elementals may be automated to conduct repairs on damaged sections, and these magical beings may persist long after the original dwarves have long since departed.

Water is absolutely essential, and multiple sources are needed on every level. Several should have open access. Watering holes are dangerous areas and key hunting grounds, as such most creatures won't want to build their lair over one due to the high traffic... unless it's fortified and within established turf. 

There are a competing priorities when planning a level: 

1) Verisimilitude. You want the space to feel believable, at least on a superficial level. That means food sources like fungus, airflow, water and light sources, etcetera, as described above. Hazards like anoxic areas, methane pockets, moulds, fungus, slimes, and so on help build the environment. Suggest some kind of an ecosystem. 

2) Functionality. This is akin to 1, but more purpose driven rather than environmental. Dwarven mines and forges should be laid out (vaguely) logically; mines would connect via rail lines to ore refineries. Kitchens would be by great halls, along with beer and wine cellars. Latrines would be separated, so the smell doesn't penetrate the living areas. Doesn't need to be perfect, just enough so that players get the idea that there was purpose driving the construction. Details like this help create that bubble of disbelief and transport player's imaginations to another reality.

3) Puzzle & mystery. Functionality is at odds with this. You want your megadungeon to be full of surprises, twists, and breathtaking vistas. Stairs that go down every level, top to bottom, make it easy for characters to move around. This makes sense from a functional point of view, but then there's no quest to find stairs. You can justify deliberately confusing layouts as part of a dungeon's defenses: levels are mixed up to put potential invaders at a disadvantage. This also inspires traps, ambush points, and other defenses. Throw in magical forces to create intrigue and mystery. Treasure vaults will be surrounded with misdirection, puzzles, and traps.

4) Awe. Strictly functional spaces don't require narrow 10 story high temples, labyrinths, or grandiose pillars of spirit infested flames. But you want cool stuff in the dungeon to capture the imagination of the players! A megadungeon has to walk that fine line between being believable and mind blowing. That's the goal, or at least my goal. 

Remember that the purpose driven design that determines the layout provides only the foundation. You can overwrite that with all kinds of awesome phenomena that occurred long after.

Next up: Populating the dungeon.

Building the megadungeon: Establishing history and purpose

What the hell is that???

I put in some more work on the megadungeon, and I've changed my approach. 

I'm getting sketchier and looser as the dungeon progresses and that initial burst of enthusiasm wanes. Arguably I should have started out this way.

Rather than working in Adobe Illustrator and creating detailed, finalized levels from the get go, I've switched to sketching them out loosely in ProCreate. Actual planning! This allows me to revise them easily as ideas occur. I can also connect multiple layers together, whereas the more laborious method using Illustrator inclined me to work only one level at a time. It's low lift and I can revise levels as time goes by, and the campaign requires me to rethink the initial designs. 

Building a megadungeon is just too daunting to do all at once.

What else have I learned?

First, you need a loose outline of the dungeon's purpose and history. This greatly helps guide layer design. Without it, it becomes random and senseless. The history of Druidun is long and convoluted, primarily in order to justify a varied environment, but yours doesn't need to be. 

All you need is a logic guiding the initial layout. After that, adjust with subsequent inhabitants and what they might have done to the original structure. Goblins, for example, might dig tunnels to connect rooms, or to follow a streak of ore, or create narrower tunnels that keep out large predators from their dens.

"Listen, Princess, I'm in it for the loot."

So what's the history for Druidun? 

The upper levels were originally dug by druids, to commune with the roots of the earth, and for their tombs. The druids expanded it to be used as a refuge during the Undeath Plagues, like Derinkuyu in Turkey, with rolling stone slab doors, extensive living quarters and even areas for animals. 

I also decided that the druids were drawn to the area by the conjunction of Ley Lines, and the powerful magical energies that existed deep beneath the surface. These energies were created by the Titans, who conducted the first experiments in necromancy in their underground laboratories and zoos, safely sealed beneath the earth. 

Later, a castle was built atop the druid ruins, and it became a stronghold for the Mercian Kings. They wanted to establish control over the magical energies below, which were studied by their wizards. They would be crowned here, to imbue their reign with mystical energy.

The wizards discovered that the intense magical energies had drawn Xorn to the area, long ago, and the hulks of dead Xorn made the earth rich in all manner of minerals; it also created magical ores thanks to the conjunction of multiple realities. This was of intense interest to the dwarves, who were brought in by the human kings to mine the earth and build a panopticon prison to house rebels and malcontents of the Mercian regime. These poor souls were also subjected to magical experimentation.

The dwarves called the site Karak-Thun, and it became fabulously wealthy. Eventually, they dug too deep, breaking into the Underdark. Powerful magical energies, chaos leeching in from beyond, had imbued the creatures in the area with great size and power, and mutated others. The dwarves were driven back by a flood of giant spiders and other horrors. A war went on for centuries, until finally the dwarven colony collapsed, the survivors fled, and the wealth was abandoned to chaos. 

More recently, a rogue order of wizards moved in to conduct magical experiments, and they opened up an energy nexus to other planes; eventually they were shut down by the Thaumaturgical Order. But the nexus remains open, and it's pumping into this reality powerful magic, resulting in an outbreak of the undead.

That's a brief overview. There's more, although arguably there shouldn't be. It's just meant to provide me with a number of threads to pursue when designing levels. 

You only need a high level background. Mine is probably too complex and convoluted, but it allows lots of variety. 

"Yes, it may be the Pool of Infinite Evil, but that doesn't mean it isn't drinkable."

Next up: level design