Random Dungeon Generators Part 1

Random Dungeon Generators Part 1

Hello, and welcome again to another edition of the Map Mine. After a brief hiatus (due to Extra Life 2023, replays of which will be up soon) we're back to bring you some random map generation techniques from various games.

In this two (or three?) parter, I'm going to use the dungeon generation techniques from three different systems and then compare them to one another. Some of these generation techniques can go on for quite some time - so I won't follow them all the way to the end in each case, but will take them far enough for you to get a feel for how the generation techniques work.

The three systems in question are:

  • Dungeons and Dragons 5th Edition - rules in the DMG
  • Shadowdark - Rules in the Core Rulebook
  • Four Against Darkness - where generation is the name of the game

Setup Time - let's get to dungeon drawing

A picture of a table with a Dungeon Master guide to the left and a Supernote A6X to the Right with dice and a pen between them
An Evening of Drawing Awaits

I decided to try and do this the traditional pen-and-paper way, with the Supernote A5X being the substitute for the graph paper. This quickly spiraled out of control when I started generating really large rooms right off the bat, but the writing feel of the newest models is really nice for doing this kind of generation. Maybe if I had scaled it down a bit, it would have been easier to manage - but failing that I decided to switch to Dungeon Scrawl.

But for fun, let's see what I drew on the Supernote:

I failed real hard at drawing on the Supernote

Dungeons and Dragons 5e Generation Techniques

If you have a look near the back of the Dungeon Master's Guide, you'll find a couple of pages of instruction for generating random dungeons using their techniques. Mostly, it's a series of tables that you roll on to determine the shape of rooms and corridors. In a nutshell, here's how it works:

  1. Start by rolling on the "Starting Chamber" Table to get a entrance room (I rolled a 40' diameter circle, yay!), which has a fixed number of exits.
  2. Pick one of the exits and start rolling on the corridor table to determine how long it is - additionally roll on the "Width" table to find out how wide the corridor is (sometimes the corridor will have columns).
  3. Continue rolling to expand the corridor until you encounter a "Chamber" or "Stairs" result. Once you do, roll on the relevant tables.
  4. The Chamber table will have a number of Exits, and for each exit you must roll for the position of the exit, and the type. There's a 50% chance it'll be a door, otherwise it's a corridor.
  5. Continue resolving corridors and rooms until the map loops back in on itself, or you've reached your target size.

It's very straightforward, and relies heavily on tables to do the generation, but as you'll see in the example, you're going to have to take some creative liberties and make some executive decisions in order to get a workable dungeon.

Time to Make Ourselves a 5e Dungeon

There's not a lot of guidance in the DMG for generating different kinds of dungeons, so I decided to go with a pretty standard "man made structure" concept.

If you'd like to follow along with the process, here's a .ds file that you can load into Dungeonscrawl:

Entrance to the Left Portion

So, starting from that 40' x 40' chamber I mentioned above, I worked on the top and left exits in a semi-alternating fashion as they started to converge.

The top corridor wound up branching off a side corridor, and then turning right and dead-ending into a Chimney. Since I wasn't really planning on making this a multi-floor dungeon, I decided to make this an alternative vertical entrance, a straight drop from the ceiling. Normally I'd use affinity to mark this out more clearly, but since I wanted you all to see it I used the stairs tool in Dungeon Scrawl.

The left passage, on the other hand, immediately turned into a 40' wide hallway, replete with columns. It eventually took a sharp right turn. I saw this was likely to run into the side corridor from the top chamber, I decided to continue on that side passage. Eventually it wound up having a side door on the left side of the passage... which was doing to dead-end directly into the other corridor. So I just merged them. That side corridor also wound up hitting some stairs, leading downward into "a chamber" - which I've omitted.

Here's what that final portion of the map looked like. So far, nothing too out of the ordinary:

A portion of a map showing what is described in the previous two paragraphs

Right Corridor, Spiraling out of Control

So, now we need to head the right door from the starting chamber and see what's there.

The first thing I rolled when rolling on the "What's behind the door" Table (yes, there's one of those too) was a 40' x 40' square with 3 exits. Each of those exits wound up being a door, and a combination of corridors and chambers. I'll let you review the next image for the less interesting parts, but the most interesting thing was a 50' diameter circle.

Sidebar: An astute observer might note that the instructions are a 40 and 50' diameter circle, and what I've done is a radius. I realized my mistake about halfway through the dungeon (including a giant hexagon), but I decided I really liked the giant chambers as a map feature so I decided to leave it.

So, this now giant circular chamber presented an immediate problem - it overlapped with one of the other corridor. I decided that means the corridor in question has a slope, which leads to an interesting feature in that other circle.

Here's how that wound up looking:

Subsection of the map described above, showing big circular chambers.
Accidentally big rooms are neat.

It just keeps going and going

So there are two other sections I'll call out before I decided that I'd had enough examples to show for this post. The bottom portion of the map wound up winding back towards the other entrance - to the point where I decided that this would make an interesting "secondary entrance" - implying there is an exterior courtyard or something else with two nearby entrances. Here's how that looks:

Lower portion of the map, with a few interconnected chambers and another Entrance

The other section in question is the other section of rooms, where I generated a hexagon and rolled a 20 on the number of doors - a full on 6 doors coming out of the hexagonal chamber (which I also made double the size it should have been).

It's about that time I decided to call it "done" as an example of how the random generation process can just keep going and maybe generate you some looping elements in the process.

Here's the full map:

Wrap Up

So as far as random dungeon generation goes, I think 5e's method is relatively simple, and though the tables themselves are fairly short (leading to a lot of repetition in the corridors and chambers it'll generate), it's very serviceable. It's also fairly quick once you get in the groove: this particular version took me about 45 minutes to generate the number of rooms for this post.

In fact, one of my upcoming adventure modules - The Corrupted Temple of Una - was generated in part using this method.

Next time, we'll be looking at Shadowdark's generation method, which uses a method of tossing dice onto paper and using the results of that die roll to generate the rooms. See you then!