Monday, October 1, 2012

Random Dungeon Stocking

Today I'd like to consider rules for semi-randomly stocking dungeons. I'll start with what I currently do, and then consider the history of such rules in the classic D&D book.

Delta's Rule: On a standard piece of graph paper (30×40 squares), I seem to get about 40 rooms or so, that will be dealt with in groups of sixths (i.e., about 6 rooms per category). First I make a list of about 6 "special" rooms I want to place (major sites, or monster clan lairs, usually with significant treasures); about 6 tricks or traps along the way (often corridor/navigation blockage or misdirection); and about 6 mundane "guard" areas in conjunction with the specials. Then I actually draw the map and place these indicated areas, filling about half the rooms of the map. Then I go through the remaining half of the areas (usually side-rooms, rarely main thoroughfare chambers) and roll dice: 2-in-6 indicates random monsters from the wandering charts (or semi-random; move or up down the list to something that generally fits). A second roll indicates treasure, 3-in-6 for monsters and 1-in-6 for otherwise empty rooms. If this random method comes out to greatly more or less than the expected 6 rooms or so (again, 1/6 of the total) then I go back and add some or take some away for the right distribution.

The end result of the preceding is 1/6 each "special" (major areas), 1/6 tricks/traps, 1/3 monsters (half selected guards, half random), and 1/3 empty -- which you'll see replicated in many of the classic rules below. One thing that's added for me are the pre-planned mundane guardrooms, which serve to flesh out the "theme" of who controls that part of the dungeon, and serve as buildup and clues to the major "special" lairs (trying to do that part randomly just doesn't build a proper theme). I think the overall effect is similar to Gygax's B2 or G1-3, with a primary monster type in each region, a general buildup to the encounters, and various and sundry surprise lurkers in the side areas (with perhaps somewhat more empty rooms).

Original D&D: OD&D is most similar to what I do above. It says, "It is a good idea to thoughtfully place several of the most important treasures, with or without monstrous guardians, and then switch to a random determination for the balance of the level" (Vol-3, p. 6). The random rolls are identical to what I use above (2-in-6 has a monster; 3-in-6 monsters with treasure, 1-in-6 otherwise empty rooms), with a helpful table provided for these treasures (balanced by dungeon level, and quite different from the otherwise well-known Treasure Types intended for large wilderness groups).

One thing that's missing here is the overall monster distribution-- how many of those "special" areas are expected? A second thing is that there's no stated allowance for tricks/traps, although a list of suggestions comes immediately prior to this section. One very interesting thing about that list of tricks/traps -- they're almost all navigation-misdirection elements that are most likely to appear in a corridor (e.g., false stairs, slanting passages, sinking rooms, teleportation, etc.). Using that as inspiration, it's one reason I feel compelled to decide on a list of traps prior to mapping the dungeon; the plan of the corridors and rooms is intimately tied to what navigational trickery is possible. But keep in mind that "specials" as used in Original D&D means the major treasure caches and monster lairs, not weird magical trickery, as the phrase might be used later.

Dungeon Geomorphs: Gygax's Dungeon Geomorphs product (featuring the older "use-every-space", thin-blue-line wall design for the basic dungeons) has stocking suggestions on the inside cover. It says: "Roughly one third of the rooms should remain empty. One-third should contain monsters with or without treasure (possibly selected randomly using the Dungeons & Dragons Monster & Treasure Assortment), one-sixth traps and/or tricks, and the remaining one-sixth should be specially designed areas with monsters and treasures selected by the DM (rather than randomly  determined). Slides, teleport areas, and sloping passages should be added sparingly."

Note that these are the same overall distributions as I use today. One mistake I made in the past, I think, was to take this a simple random d6 roll in every area of the map (1-2 empty, 3-4 monsters, 5 trap, 6 special). The problem with that is that it handcuffs you into doing work to freshly invent traps and specials at times you don't want and places that don't fit (there being no random follow-up method for those). Moreover, the all-random monster method produces no intelligible theme or pattern, so nowadays I fill at least half of those intentionally beforehand (pretty simple, mostly just duplicating the "special" types).

Monster & Treasure Assortment: This collection of treasures to be used in different dungeon levels has a different distribution suggestion on the cover: "However, it is recommended that the DM selectively place as many treasures as possible, doubling up in some cases, and augmenting the whole by noting where and how the treasures are protected and/or hidden. It should also be noted that just as a dungeon level should have monsters in only 20% or so of the available rooms and chambers, about 20% of the monsters should have no treasure whatsoever."

It seems to me that having monsters in only 20% of the rooms is way too low and wasteful. I don't think any other product ever suggested such a low number, and I think it can be pretty much ignored. Note that my current rule places monsters (specials, guards, and random) in 3 rooms in 6, i.e. 50%, or more than twice as many as suggested by the MT&A rule. With my rule 1 room in 3 is empty, which some people might already consider excessive. Furthermore, while it explicitly talks about the DM selectively placing only treasures and not monsters, it would clearly be a significant error to just go through a dungeon level rolling 2-in-10 for all the monster placements.

AD&D Dungeon Masters Guide: Again, no global dungeon distribution rules are given, although we can see a table in Appendix A: Random Dungeon Generation that gives some clues (p. 171). This table uses a d20 roll, with results of 1-12: Empty; 13-14: Monster only; 15-17: Monster and treasure; 18: Special (or else stairs), 19: Trick/Trap; 20: Treasure.

A few comments: This seems to be similar to the MT&A rule, with fully 60% of the rooms empty, only 25% with any kind of random monsters, and just a tiny number of specials or tricks/traps. In practice this seems incredibly sparse, and when using those rules I personally increase the numbers of non-empty results. One obvious sticking point are the "specials" which have no random method for completing them, and would be an outright conflict of interest for those playing a game solo by those rules. However, this does lead to the fascinating rule, "For special areas you can have a friend or correspondent send you sealed information." (p. 173)

Holmes Basic D&D: The "blue book" Basic D&D by Eric Holmes somewhat surprisingly doesn't have any distribution suggestions. It has a very short couple of paragraphs on Dungeon Mastering as a Fine Art, where it states that "the Dungeon Master must sit down, pencil in hand, and map out the dungeons on graph paper... the introductory module 'In Search of the Unknown'... will be usable for initial adventuring as well as provide ideas for dungeon construction" (p. 39). My understanding is that earlier version of the D&D Basic set instead included the Dungeon Geomorphs product (above), which would thus pick up the slack both for mapping and distribution suggestions.

Moldvay Basic D&D: Moldvay's "red book" rules give a detailed step-by-step process for creating a dungeon, starting with: A. Choose a Scenario (listing 10 themes), B. Decide on a Setting (6 types), C. Decide on Special Monsters to be Used, D. Draw the Map of the Dungeon, E. Stock the Dungeon, and F. Filling in Final Details. In the Stock the Dungeon stage, he says, "Special monsters should be first placed in the appropriate rooms with special treasures. The remaining rooms can be stocked as the DM wishes. If there is no preference as to how certain rooms are stocked, then the following system may be used" (p. 52). This system is (as usual) determined by a d6: 1-2 Monster, 3 Trap, 4 Special, 5-6 Empty (treasure is indicated 3-in-6 for monsters, 2-in-6 for traps, and 1-in-6 for empty rooms). Traps and specials must be developed by the DM, but lists of ideas follow (e.g., navigational hazards a la OD&D, moaning room, talking statue, flying weapons, etc.)

Most of the time I'm highly impressed by the clear and detailed understanding that Moldvay provides; but here I think he falls down a little bit. First of all I'm not fond of the random method creating design work for the DM in 1/3 of the cases (traps and specials), since in theory the random generation should be relieving and completing the DM's labor, not making more of it. Secondly he's mangled the notion of "specials" a bit, using the phrase both for specially-selected major monsters and treasure, as well as randomly-indicated weird trickery, which is not terribly helpful. Using this in the past caused me quite a bit of frustration -- I'm not sure that drawing the map first, and then having traps randomly placed and determined (really unique to these rules except for the very small number in the DMG solo section), is the way to go. Furthermore, at the point where the DM turns to random stocking, the random system really needs to be a complete turnkey solution (and not demanding more work of the DM).

So, what system works best for you? (By the way, this marks the blog's 400th post. Thanks for reading!)


  1. I have been using Moldvay, with the important caveat that major/themed/"special" encounters (including "guard" rooms) are designed without randomizers, and the randomizers are only used to fill in the areas leftover.

    To avoid doing additional design when using Moldvay's method, I wrote up short traps and tricks tables, so that those could be randomly determined as well.

    I started out using no randomizers, then switched to the OD&D method, then switched to Moldvay, because I like having a chance for traps and tricks in the leftover areas of the dungeon. I agree that without additional tables Moldvay's method would be inefficient. Moldvay should also only be used to fill in the dungeon after the major/themed encounters have been designed.

    The "emptiness issue" has been preoccupying me of late. For whatever reason I have been loathe to include many empty rooms in the dungeon. It does make sense to include empty rooms from a game-play perspective, though, to create variety and pauses between the action. But leaving empty rooms in the middle of an inhabited part of the dungeon seems weird to me, as if the rooms are being "wasted". I can think of a dozen things the occupants of the dungeon would do with that space! Guard rooms, storage, prison cells, shrines, etc. As a consequence of this attitude, I think my dungeons have been too densely packed. One-third empty sounds about right to me.

  2. "I wrote up short traps and tricks tables, so that those could be randomly determined as well."

    Totally agree that's a fair solution; Moldvay should have included those (although I assume it takes quite a bit of space for tables for different level-difficulties).

  3. I used the Moldvay tables until I picked up the Mentzer Basic to finish my BECMI collection. In my DM's book, someone had numbered the examples listed for traps, turning them into a useful table. This has worked pretty well when no other idea lent itself. For Specials I usually turn to the 1E DMG for inspiration.

    As for monsters, I typically have an idea of what sorts of monsters are found in a given level or area, and make a local random encounter chart which I use for stocking as well. I try to include an entry that points to the basic charts in Moldvay, in order to ensure that I can be surprised. (Doing this led to my tentpole dungeon's second level - originally intended to center around a goblin lair - to include a major nest of giant ants. The party's efforts against the ants were at least as great an undertaking as the raids against the goblins.)

  4. I've been using the OD&D method, liberally peppered with results from tables from other sources, particularly the AD&D DMG.

    For the non-random design (particularly the "specials"), I try to draw on James Mal's Old School Design Guidelines as much as possible (

  5. Just saw this post. I think you missed the Holmes guidance - it's at the top of page 40. It's a summary/reduction of the OD&D rules: place special items first, rooms have monsters on 1-2 in 6, clean-up crew are randomly placed mostly in corridors, wandering monsters determined during play. The Sample Dungeon roughly follows this by having eight empty (E) rooms.

    1. Good catch! Of course, it was right on the flip-page from where I was looking for it. :-/

  6. Moldvay has always been my tool of choice, but that's probably b/c it was my first. Even after using AD&D for a bit I went back to Moldvay. When the lists weren't numbered I'd roll and count through the options as if they were. What's funny is that Moldvay's inefficiency was actually something I viewed as a benefit -- I enjoyed the time spent in the dungeon before use and found that any number of new ideas would occur to me while tinkering w/ it.

  7. Back in those days, I always designed every room. Just recently I've been finding posts like yours above really influential and am about to modify "Falun Caverns" from The Northern Reaches. I figure the kobolds there have done some tunneling and structure building. Anyway, I plan to do a bit of a hybrid between planning and Mentzer/Moldvay. Can't find my Holmes book which makes me terribly sad.

    1. Thanks for the feedback, I hope that helps your game!

      P.S. As I write this I can see some copies of the Holmes Basic D&D rulebook on EBay for $5 or $20 (once you look past the $250 boxed sets and so forth).

  8. I think you misread OD&D, you roll twice, first to see if there's a monster (on 1-2) and then to see if there's treasure (1-3 if there's a monster) with only a roll of 1 in an unoccupied room indicating treasure, so 20/36, or about 55% of all rooms are empty using this method.

    1. I think that's the same as what I said? "Delta's Rule: ... 2-in-6 indicates random monsters from the wandering charts... A second roll indicates treasure, 3-in-6 for monsters and 1-in-6 for otherwise empty rooms... OD&D is most similar to what I do above."