How I Rebuilt My Sewer Temple to the Chaos Frog

Procedurally generated content is a great way to prep for a game session in a hurry. Early D&D is rife with procedural rules; the earliest rulesets contained wandering monster tables for generating opponents and treasure tables to determine what phat loots those monsters have. The 1e DMG goes even farther by presenting a set of tables for generating a random dungeon map!

Computers, of course, are great for speedily generating random content. Community-oriented players have put up all sorts of free web applications for DMs. One such is “donjon”, a program that generates dungeon levels to your specifications in the blink of an eye. Not only can you set the parameters for how the place should be laid out, you can populate the place with monsters and treasures as well.

Computer-generated procedural content is not without flaws, of course. One is its lack of flexibility. If you’re sketching a dungeon map by making random rolls on a table, you’re free to diverge from the table results and interject your own ideas while drawing the map. A computer-generated map is not so flexible. Nonetheless, you can make changes—if you have the right software.

Map of 'The Temple of the Frog' (original)It was the day before the session and one of the players had decided to bite on a plot hook involving a group of Chaos worshippers congregating in the sewers of Glantri City. After a desultory attempt at sketching a map for a section of the city’s sewers, I decided to try an online map generator. After several minutes of fiddling with donjon and learning its settings, I came up with the map on the left. Since I wanted a short dungeon (as per David Bowman’s “One Page Dungeon”), I’d made a map with only a handful of rooms, but they were encircled by lots of winding tunnels to give that “lost in the sewers” vibe. (Click for a better view.)

But I was unsatisfied with the map as it was. It was too flat, too static. It also needed connections to the rest of the sewer system. So I started up Adobe Photoshop and started tweaking.

Map of 'The Temple of the Frog' (modified)First, I filled in the sewer tunnels with gray to represent sewage. Several rooms and corridors remained white to indicate that they were above-water cellars, and I added stairway segments where they connected with the sewers proper. With only a few more water squares, I joined up some otherwise unconnected tunnels and provided links at the borders to the rest of the sewer network. The dark gray gridmarks in the sewer system’s dead ends indicate street access points via drainage gratings. Lastly, I added a couple of new rooms, including a large “sump” room (#7 on the modified map on the right) designed for a dynamic fight scene against Chaos-tainted frog monsters, with a walkway around the edge of the water and a treasure on the stump of a big broken support pillar in the center.

The whole mapping project took less than two hours from start to finish. Another one would go faster now that I’ve gotten a feel for how to go about it. I think, though, that my next map will be completely procedurally generated, as I’m looking forward to being stuck with a premade map and having to find a way to use it as-is. Limitations and restrictions are important for any creative endeavor!


5 Responses to “How I Rebuilt My Sewer Temple to the Chaos Frog”

  1. December 2, 2009 at 3:26 pm

    Given the relatively limited number of monsters in Red Box, it should be pretty easy to completely stock a dungeon using a random method. I’m surprised it doesn’t exist already…

  2. 2 Mr. Grengoat
    December 2, 2009 at 4:15 pm

    The Donjon link that Eric provided does actually generate the whole dungeon she-bang with D20 monster stats, treasure, and door types. Impressive bit of web free-ness.

    I always felt that random monster placement were always the most wonky part of procedural dungeons. As A DM I can explain away a whole load of whacked out architecture and rooms but when the tables place juicy cows next to a room full of ravenous somethings and then undead a door down from that, it’s hard to pretend there is some narrative logic to the place.

    Linked themes in the monster tables work much better (which the donjon site indeed does).

  3. December 2, 2009 at 4:55 pm

    I usually assume that the weird results are due to being a moment frozen in time. It’d be fun (and perhaps not too much work for a small dungeon) to advance the likely course of events one turn at a time along with the PCs’ action on each turn. The PCs kick down a door; the somethings go next door and eat the cows (which they followed into a hole in the ground not long ago). The PCs hear the noise and run down a corridor; they arrive just as the undead open the door in order to feast on the somethings (as they have been waiting in the dark for eons to do).

    The fact that the PCs always arrive on the scene as these coincidences happen strains credulity, but in a fun way no one is likely to complain about IMO.

  4. December 2, 2009 at 6:19 pm

    When used sparingly, procedural monster placement can yield interesting and unexpected results without straining credulity; the trick is to use these placements as seeds rather than filling the entire dungeon with random results. Once you know there are gnolls or oozes in the dungeon you can place more around them, etc.

    In module B1 ([In Search of the Unknown]), the DM is expected to populate the dungeon from a list of 25 monsters. When my Glantri group [unexpectedly entered Quasqueton] before I’d fleshed the place out, I rolled randomly to see what they encountered. When an elegant bedroom proved to contain a shrieker, I decided that the room’s plumbing (a fountain-like water basin specified in the room description) had overflowed and soaked everything, allowing fungi to grow over everything. The result was flavorful and gave an added sense of realism to the place.

  5. December 2, 2009 at 9:28 pm

    glee! love what you did with the map.

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Past Adventures of the Mule

December 2009

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