Designing a Dungeon

Dungeons set so much of the tone for D&D and similar games. Everyone has their story of that great dungeon crawl where something amazing, crazy, or stupid resulted in one of those epic gaming memories.  We all love a good dungeon crawl. But what makes a dungeon crawl good and how does the GM design that perfect dungeon?

Dungeon design is often about balance between realism and attain a dramatic story effect. If you are rolling up a random dungeon, you are not designing. Put away the dice, cards, and random map generators, and let's do some thinking.

Only you know what you are looking for in your game for your plot. It depends on what your players want. It depends on where the story is headed. Before you get started on dungeon design, have your goals in mind. In fact, if you can, design a few rough encounters you might like to see. Leave the details for later.

A dungeon was originally built for a reason. Answer the questions: Who built this dungeon? What was it part of? Why did they build it?  Do a quick sketch, as to what it looked like when it was originally built.  What sorts of things would be in this dungeon for its original use?  Let's take an example of an old dwarven dungeon that was home to an ore processing area. They would melt down the ore and make metals out of it. It connected directly to several mining tunnels that went off to a whole network of mineshafts.

Now, let's add some time. Whatever this dungeon was originally used for are times past. Whatever this dungeon was a part of is now likely ruins or long gone. That is some seriously destructive power to raze away a castle, a fortress, or whatever else was above. These same force has likely affected the dungeon below. Tunnels have collapsed, earth has moved. Earthquakes may have ripped sections of ground apart. Water has seeped in and caused parts to sink.  Meanwhile, some new residents have moved in. Things from above and below can find residence here, safe from all except the most daring adventurers.

For our old dwarven dungeon, we will assume earthquakes had driven the dwarves away hundreds of years ago. Most, but not all, of the mining tunnels have collapsed. One has now opened to the surface to allow creatures inside.  Several ceiling collapses have provided other entrances to different portions of the dungeon.

So now, let's figure out from our encounter ideas what sorts of things we want to live in this dungeon. What kind of conditions would attract them?  If there are several things living in the dungeon, how do they survive. Will these different monsters fight against each other? If so, what natural barriers keep them apart in the dungeon. How do these creatures get food and water?

A pack of wargs has taken up residence in the entry tunnel where they stay warm in the bitter cold and still have access to the surface for hunting.  Deep in the dungeon, one room has sank and collected enough water for a small lake. Goblins have set up their village there and even have brought fish to the lake to provide food when they are too scared to head outside. The deep mining shafts and tunnels have brought in cave dwellers from below. Rust monsters now multiply in the dungeon, slowly eating the dwarven metal tools and metal doors.  A roper and cloaker have also set up homes, not too far from the goblins, where they can catch one now and then when it wanders too far from the village.

The best details come when we combine the old with the new! The goblin village uses old mining carts for the huts in their village. The cloaker has taken up residence in a room where the old leather cloaks of the dwarves still hang. Goblins have gathered old dwarven mining implements, with handles long rotted away, and made traps to keep longshanks and large monsters out.

Now, we just need a map. The map is really what sets the tempo and the choices for the PCs, so we can set a lot of the tone. How many ways in (and ways out) do we give the PCs? How far do the PCs have to travel to meet the goblins or other inhabitants? How far will they have to run to retreat away from them if things go poorly. Will they have multiples paths so they can bypass encounters and traps? Will the paths be easier to traverse in one direction as compared to the other? Keep in mind that a dungeon is a three dimensional structure. Climbing is a good skill to put to use.

Also, as you draw the map, keep in mind that the PCs are undoubtedly a disruption. Trodding through, ripping open tunnels and doors, they are changing an unchanging world in a drastic way. With this disruption comes all sorts of consequences. Tunnels may collapse. Spells and traps may be triggered. In our Dwarven dungeon, the PCs may run into those rust monsters and find their only escape is an old dwarven lift. Too much weight and attacking rust monsters may leave them plummeting into the unknown. Knocking a hole in a wall could empty that goblin lake right into the room their in. Nothing is static. Any next step could cause major changes to the dungeons, unleashing new threats and blocking paths, including ways out.

As you pull together the final concept, throw in some details, things to both make the dungeon real and to detract from threats. There may be dwarven stonework of master miners lining certain rooms. Piles of old ore and materials may lay about. Books in sealed rooms might have dusty old pages that still tell stories of the mines, the kingdom of the times, maybe even treasures that might be found. Right down lines of description and ideas, complete or not. You never know what you might need to improvise out of your notes. No GM plan ever survives contact with the PCs, but it will go well, because you have prepared a well designed dungeon.