How Dungeons are Created

First, you can put as many pre-placed design elements into the dungeon as you like, such as guaranteed-open spaces, or rooms and walls. You can use these to place special NPC's and other story hooks, for which you want a specific environment. The DungeonMaker then constructs a random dungeon around these pre-placed elements. This is done by a population of Builders, little alife-agents which scurry through the dungeon, leaving walls or tunnels in their wake.

Where the background of the dungeon is open, Builders of subclass WallCrawler (referred to as Crawlers) are active building walls. Where the background is closed, Tunnelers do their thing. While Crawlers only spawn other Crawlers, Tunnelers also spawn Roomies, which (surprise!) make rooms. This whole process is governed by a large number of parameters, which are specified in a design-file.

Every Builder belongs to a specific generation, with generation X starting its life only after generation X-1 has died out. Builders die either because they have run out of space, or because they have reached their maximum age. While they are alive, they make a series of steps, which consist of building a stretch of wall or tunnel, possibly changing direction, and possibly spawning one or two babies.


The behavior of a solitary Crawler is dominated by the parameters corrWidth (which determines how much space it leaves between the walls it builds and other closed squares), stepLength (which determines how many open squares it can fill with wall squares each step), and changeDirProb (which is the percentage of cases in which this Crawler will change direction at the end of a step). The first two parameters are the same for all members of one generation, whereas the third is inherited (with some random mutation) from the parent Crawler. Inherited parameters make it possible to have labyrinths with different characteristics in different regions (depending on the parameters of the design Crawlers which are the ancestors of their respective regions), whereas per-generation parameters help to ensure that Crawlers work well together and make it easy to enforce a desired frequency of walls/open spaces in a design.

Crawlers can come into existence as design Crawlers, whose parameters are specified in the design file (overriding parameters normally determined by generation), or as RandCrawlers, which randomly start off the edge of the map. All RandCrawlers have the same inheritable parameters, and in the design file we can specify the probabilities with which they will be born in any given generation. While design Crawlers can be "closed", which allows them to join an existing wall and thus makes it possible to block a passage, all RandCrawlers and baby Crawlers are "open", and must leave an opening at the end of their run. This means that, unless the designer has placed closed Crawlers in the wrong place, the Crawlers will never cut off a part of the labyrinth. Everything is guaranteed to remain accessible.


Tunnelers are much more complicated than Crawlers. While Crawlers only build walls that are one square wide, Tunnelers can build tunnels of any uneven width. They can also build anterooms, which are most often placed in front of rooms, or at the intersection of tunnels, and which I envision to be places where the MOBs (mobile objects inhabiting the dungeon) meet and socialize. Finally, they can spawn Roomies. Roomies are Builders that make just one step, or none: If they see enough closed space for the size of room they want to excavate, they build their room in one fell swoop when their generation comes alive, otherwise they self-destruct.

Tunnelers only come into existence as design Tunnelers, or as babies. Usually there's one design Tunneler starting at every entrance to the dungeon that leads into an area of closed squares, and at every door to a pre-placed room in such closed areas. While Tunnelers are fond of joining with each other and of busting into rooms, in general there is no guarantee that they will do so, and it is possible that the tunnel systems made by two Tunnelers and their offspring will never connect. If one Tunneler starts from a dungeon entry, and another from an exit, then the software that uses the DungeonMaker will have to test that the two points have in fact been connected, and run the Dungeonmaker again with another random seed if they are not. This is a special case of a playability-test, which we expect to implement for any commercial use of the DungeonMaker, and which would generally test for more criteria than mere connectedness.


After all the Builders have run their course, the DungeonMaker can do two more things. It can place rooms in open areas that have been worked by Crawlers - this is done by searching for areas that can be turned into closed rooms by placing a door in a single square. And then it can place treasure and MOBs. This process will have to be fine-tuned for every single game the DungeonMaker is used for, and has been implemented as a generic demonstration only. While the Dungeonmaker can place treasure and MOBs of an unlimited number of categories, the graphic program boils it all down to 3 colors each, with the more lively colors being used for bigger treasure and MOBs.

The demo program that presents the output of the DungeonMaker shows the construction of the dungeons as a movie. This is interesting to watch and, if you watch it enough, will give you a deep intuitive insight into the dungeon creation process. I was able to greatly improve on the performance of the Crawlers in version 2 after having watched their version 1 brethren do their thing thousands of times. Tunnelers are new in version 2, and a similar improvement in future versions of the program seems possible - I have a few ideas, but before I radically re-write the Tunnelers I want to ponder them for a few months.

The demo program recognizes 3 command line arguments: ' -d ' gives extra information which is useful for the design-process, and ' -+ ' and ' -- ' can be used to scale the size of the map - ' -- ' makes the map smaller, and will speed up the dungeon movie. After the program has presented a dungeon, you must close the window where it is shown, whereupon you will be presented, on the command line, with the choice to enter 'q' for 'quit the program', 'n' for 'next design', or 'r' for 'repeat this design with a different random seed'. I urge you to choose r as often as you have time and patience in order to see both the variability and the similarity of dungeons made from one design file.

On the following pages we show examples of the dungeons constructed from the design files that come with the program, we comment on the designs, and explain as many important details of the program as we can think of. We recommend reading these pages concurrently with running the program, like this:

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go forth now and
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yourself with the DungeonMaker
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