Underworld Hexcrawl as Streetcrawl

JDJarvis at the Aeons & Augauries blog and Beedo at the Dreams in the Lich House blog have been talking about creating large, sprawling megadungeons by using what they call a “node” approach to design: create areas of interest (nodes) that might be considered a typical large dungeon, if used separately, and connect them with long tunnels, which may have small dungeons sprouting off along the way, but these can either be improvised as needed or you can have a book of prepped, one-page dungeons to drop in whenever an encounter roll says you find a place of interest during your “underground hexcrawl”. I tried something like this once before, although I got dissatisfied with that example megadungeon I was building and later started talking about other ways to flesh out a sprawling underworld.

I didn’t use the term “nodes”, which might be better than the “megamodules” I was talking about once… and the dungeons in between my nodes/megamodules were more like small waypoints, which is not what I think either JD or Beedo are getting at. I think they are not talking about long underground features – great chasms, mile-long tunnels, underground rivers – with 1 to 3 tiny dungeons along the way. I think they mean more like a solid maze of tunnels extending for miles, with the entire maze being treated as a hexcrawl, only describing individual tunnels as needed. Something like: “The goblin king tells you that if you travel through the Great Rift, you will eventually reach the Obsidian Gate to the kingdom of trolls”. And along the way, you mention many caves in the sides of the Great Chasm, but don’t map out or describe them unless the players pick a random cave to explore or make camp in.

What I think might be applicable here is to use the urban crawl rules from Vornheim. Put your nodes on the big sketchmap first, then draw lines connecting the nodes. Each line represents one route through a maze of twisty passages, all alike. On one side of a line/route, write out numbers from one to six, one to ten, or one to twelve, whatever fits, in an arbitrary order, as you would for neighborhoods. Do the same for the other side of the line: you can either repeat the numbers in a different order, so that you can have a Three East and Three West, for example, or split numbers between the two sides without repeating “neighborhoods”. So, you have something like:

      X
      I     VE
THREE S ONE FI
_______________
FOUR       TWO

… But with the letters butting up against each other, so that they connect.

On the outside of these “neighborhoods”, use a second set of words from a short descriptive phrase, like “UNDEAD WORM PITS”. This becomes a quick description of that area on the map and a rough guide to the major routes through that area. When crawling through a given “neighborhood”, use numerals for individual tunnels, the way Zak uses them for street-by-street paths through a neighborhood. You don’t need to map the individual tunnels at all, until the players decide to explore or are forced to escape into unknown areas.

Improv Underworld, Part One

I've been starting to think about the problem of using the sketchbox dice tool for an improvised underworld, similar to using it for improvised towns and villages. Most of what I've described so far deals with using the dice tool as an aid to prep, but if we want to truly leave most of the underworld vague or unmapped, we need a different approach.

Step One: Write down one to three general statements about the underworld. These should just be short phrases, like "unhallowed necropolis of the demon-prince" or "fallen city from centuries ago". One of those statements should suggest the reason why the underworld fell, such as "flooded by slime" or "buried by earthquake". The exceptions would be if it's merely old and forgotten (abandoned because of climate change or economic factors,) or if the underworld was never above ground and was built by its current occupants. Another phrase or statement could suggest current distinguishing features, like "tainted by visible, glowing evil".

Also pick a starting size (equivalent to hamlet, village, town, city, metropolis.) This, in combination with the statements above, will give you a general grasp of what's going on down below, enough that you could start a vertical level cross-section.

Step Two: Write down a couple nearby/connected underworld areas. A one-phrase summary for each of these will do for now. These can be on the same level, connected by tunnels, or below the top level, connected by pits, chutes, ramps, and stairs. If you are doing a cross-section, add these where desired.

Step Three: Write down one to three general statements about each quarter of the starting underworld. One of these statements should say what is unique about the appearance of that quarter, such as the typical size/shape of a commoner's home and how roads are constructed.If there is a Focal/Special quarter, it will have an original purpose. If the current occupants are different, you may want to convert a different area to cover a new main purpose.

Step Four: Roll for or select the state of decay or ruin for each quarter and each connecting tunnel, including tunnels leading to other levels or nearby underworlds. For any quarter connected to the surface, use a base 2d6 roll, +2 if you intend the level to have intelligent occupants, -2 if you want to start with a more abandoned feel. Then, roll for any tunnel connected to one of these starting areas; use the unmodified roll if the adjacent area is Average condition, add +1 to the roll for every adjacent area in Good condition (+3 per Very Good,) subtract -1 from the roll for every adjacent Bad area (-3 for Very Bad.) Continue to roll for areas these tunnels connect to; if a tunnel is blocked/collapsed, only roll for the immediately-adjacent, isolated area, then stop; you can leave areas connected to an isolated area until later.

(Step Four-Point-Five: If any tunnels are sealed, decide how they are sealed. If the tunnel leads to another sublevel (adjoining underworld,) it's probably leagues long, so consider using the Lake/River or similar obstructions. It's important to do this when necessary before Step Five.)

Step Five: Build your wandering monster lists for each quarter. The decay status of the quarter tells you what kind of monsters might work best, as will the method of obstruction for some tunnels. Areas that are close to each other will probably have overlapping monster types. More distant areas will have little or no influence.

These steps give you the basic concept of your underworld. I'll continue in Part Two.

Sealed Tunnels

When I talked about rolling for the condition of an underworld tunnel or area, I said that a Very Bad result for a tunnel indicated a collapsed tunnel. But actually, there are a number of different ways that a tunnel might be sealed off, mostly depending on factors specific to the environment or your general concept:

• Flooding: Tunnel dips down and water or some other liquid has sealed it off. Doesn't block amphibious creatures, so a completely sealed-off section might add amphibians to the vermin typical of such areas.
• Poison Gas: Not physically impassable, but anything that requires air will probably die attempting to pass. As a consequence, much more impassable than Flooding.
• Ice: Flooded, then frozen. Actually pretty impassable until cleared, but clearing it will probably require protection from the cold.
• Mud Flow: Works like Flooding, but amphibians aren't permitted. Creatures that can hold their breath (or don't need to breathe) could pass, however, as long as the mud is still soft. If the mud has hardened, it's pretty much the same as a collapsed tunnel.
• Lava Flow: Much more extreme than Flooding. Only the exotic, enchanted creatures that can swim in lava can pass through such a tunnel.
• Chasm: Quake other catastrophe has left a wide  (50+ feet) gap in the tunnel, preventing access; there may have been a bridge that is now collapsed. Much less isolating than Flooding; any creature able to fly or crawl on the ceiling can pass back and forth. There may even be enough flying animal traffic to guarantee a food supply for an isolated, primitive humanoid tribe.
• Lake/River: Like Flooding and Chasm combined. Instead of a completely submerged tunnel, there's a wide body of water (probably stocked with fish or aquatic beasts.)  There's usually something dangerous enough to make swimming out of the question. A boat or raft may help, as long as there isn't a vertical drop-off on one or both sides.
• Tar Pit: Like a Lake, but a boat is out of the question. Without special measures, anyone attempting to cross tar will probably be stuck. If the tar is boiling, there will also be damage involved.
• Walled Off: Someone deliberately sealed the passage. This will probably be harder to clear than a standard collapsed tunnel, and there's almost certainly something to worry about on one side or the other.

Ruined Tunnels

The sketchbox underworld layout and quarter divisions assume that the underworld is in pretty much the same condition it was in during its heyday. This is fine if your underworld has always been underground, or was moved underground by its primary inhabitants. When you have a ruined city from the surface that has been slowly resettled by other inhabitants, though, not everything should be in a pristine state. Some areas will be in disuse, with only incomplete indications of their former use. Others may even be partially collapsed or isolated from the rest of the underworld.

My quick solution to this bit of detail is, of course, to repurpose the 2d6 reaction roll to determine how well a district or connecting tunnel has fared. The results are:

• Good (9+): Most if not all of a district or tunnel is in use. There are almost certainly intelligent inhabitants who keep things in reasonable condition; there are signs of wear and tear, but anything broken in a previous cataclysm or stage of abandonment has been repaired (unless the current inhabitants don't understand the original use.) On a 12+, the area is patrolled and possibly well-lit, if the inhabitants need light. Doors will not be stuck, but may be locked or barred. Supplies will be in good condition.
• Average (6-8): District or tunnel is intact, but has been either abandoned by intelligent inhabitants or is in the process of being reclaimed. Accidental pit traps and deadfalls caused by disrepair may exist. Some doors may be stuck; others may be broken. Any light present will either be accidental (phosphorescent fungi or left-over magic, for example) or temporary (brought by invaders.) Areas devoted to specific crafts or other uses may still have usable tools and materials (5+ on d6.) Not everything will make sense. Inhabitants have almost certainly moved in after the area fell into disrepair; intelligent inhabitants are part of an expedition or relocation effort; they may have installed traps aroun their camp.
• Bad (3-5): Section is in ruins. Tunnels and rooms will be filled with debris, but will still be passable in general. Any but the most durable supplies or features will be unusable except maybe as raw materials (wood splinters as tinder, for example.) Inhabitants will mostly be dumb beasts; any intelligent creatures are in transit or part of a raiding party. Traps will all be of the accidental variety. Any wooden doors are rotting and should have a chance of parasites.
• Very Bad (2): Collapsed tunnel (must be cleared) or district isolated by partial cave-in. Individual rooms are collapsed on a 5+ (d6). Just about anything else could collapse, depending on a party's actions. There may be tiny passages for small vermin to enter/exit, but nothing bigger will be alive in this section. Any major inhabitants will be enchanted, undead, or otherwise extremely dangerous, since it has survived for centuries without food or water.

I recommend rolling separately for each district and each connecting tunnel. This doesn't have to all be done at once; as I've mentioned, I'm seeing this mainly as an impromptu dungeon planning technique, so you may have one small section of an underworld mapped out and some collapsed tunnels to other, vaguer sections, which you would roll for when needed.

Underworld Quarters

I explained previously how to use the sketchbox dice tool to create random underground layouts with just a few dice rolls. But that's a very basic technique; I left out how to use the quarter information in the rings to add more detail.

Without using quarters, all dice are assumed to represent the common quarter -- in other words, mostly nondescript rooms repurposed as lairs or storage, or currently empty. If you use the information in the rings, rolling as you would for a settlement, you can add:

• Noble Areas: throne rooms, treasure vaults, dining halls, other rooms designed to display wealth and power. This does not mean that the wealth is still present, or that it is easily transportable; it only defines the previous function of the rooms.
• Focal (Specialty) Areas: If you define in advance what the location was originally built for, any Focal districts will have equipment left over (or currently in use) from previous activities. Thus, if you are rolling a random mine, Focal areas will include smelters, stops for mine carts, mining supply rooms filled with rope and pickaxes.
• Craft Areas: Miscellaneous workshops for other tasks. Equipment might still be viable, even if the area is mostly ruins; if the location wasn't abandoned or was taken over by new occupants, the areas may still be in use for their intended purpose.

Thus, the quarter information defines a more structured area than the bare random roll. You can create quarter-specific monster lists, using the layout defined by the roll to determine what monsters dominate which areas. Assume that the number of d6s rolled equals the dungeon level, for the deepest part of the dungeon. Use an equal number of dark d4s and light d4s to set elevations, and reduce the dungeon level of the higher elevations. Use these numbers with the level-based wandering monster tables to determine the typical power level of creatures living in each district or quarter.

What kind of monster will depend on the conditions in that district, of course. I'll cover that topic in a future post.

Sketchbox Underworlds, Revisited

Did I mention yet how the sketchbox dice tool can be used for mapping out underworlds? I didn't? Man, that was the whole reason I started updating it, too...

The basic idea is that you use the techniques for randomly rolling village layouts to generate a dungeon or cavern system. Roll dice with pips on the sheet, each pip represents anything from one room cluster to one neighborhood; connect districts with tunnels instead of roads. Pretty simple.

For small cave systems, roll 1 die and treat it as a hamlet (each pip represents one to six caves; roll a d6 for cave layouts or randomly select a cave geomorph for each pip.) Alternatively, you could roll for elevation with d4s and roll 3 dice for cave layouts at the same time, as if you were rolling for above-ground terrain features, to establish the levels; any "level" without any six-sided dice is one large cave, and tunnels slope up/down to connect dice on different levels.

More extensive underworlds are rolled like villages or towns, treating each pip as a block of buildings or a district of 1d6 blocks. This is based on the assumption that such underworlds are the underground remnants of previously-above-ground settlements. For now, we're just concerned with rolling dungeon layouts, but in a future post I'd like to delve into interpreting the rings, rolling to see the status of tunnels and districts, and even how to do this on-the fly, so that you could leave your megadungeon notes as sketchy as the impromptu towns.

Sketchbox Underworld

I've been musing over that idea of a sprawling sketchbox underworld suggested in a previous post. This is a bit different from the "megamodule" approach to megadungeons that I suggested a while back. Sure, I still see the usefulness, even the need, for themed sets of rooms at scattered locations, but a sketchbox underworld would show a little more attention to the area around the modular parts.

The idea is: a sketchbox underworld used to be a city, so if you build it on the fly, you use the same techniques you'd use to build a standard city on the fly. Such as these techniques here. You start with an "undervillage" or "underhamlet". You map that out with some of those techniques. You use the population dice map to place other former settlements on the underworld map. You figure out what the connecting passages are like (burrows, subterranean river, wet or dry canal, chasm, rough-hewn lairs.) There would have to be a way to determine which sections have collapsed, which have been altered or expanded, which have flooded, which have become overgrown with fungus or other environmental changes.

Since I started thinking about this, I went back to the population dice map and started to redo it; I'm trying to merge it with the quarter system and the random town table, not only to make it more useful as an all-in-one town creation tool, but also to adapt it to sketchbox underworld use. Maybe I can get to the point where a GM could run a whole campaign using that tool, the Quickie Dice Tool, and GM notes created during play. The only thing needing prep would be a handful of megamodules to drop in from time to time.