Chthonic Codex: Chthonotron in action (or: how to build your own pointcrawl map)

Step 1: Some dice, pens and an empty piece of paper

Volume III of the Chthonic Codex series, Mysteries and Mystagogues sports a number of tools to build and run your own campaign. In this blog post I'm going to use the CHTHONOTRON to build my own map about my (part of the) Hypogea under the Valley of Fire. The map in the boxed set was created with the same rules. +Paolo Greco did post his own example of using the CHTHONOTRON on his blog as well.

We start with a blank piece of paper, and then toss a handful of dice as anchors for the caves to go through. Those are marked with a couple deft strokes of a pen ...

Step 2: Add some canyons carrying water

These blue lines are the water filled canyons that are the life lines of the Hypogea. Remember, everything is underground! I took the dice as inspirations where the rivers go, and I wanted to have a big lake as well, so the somewhat-forlorn-in-the-middle-of-the-sheet die I used to put a little sling around to make a huge lake. We'll see what happens there a bit later. But the rivers and canyons are not all that makes up the Hypogea: We need caves, and passaged connecting the caves. So we add those; one time for big-ass caves, and another time for smaller ones, just to make the map more detailed:

Step 3: Large caves

 One die goes off the sheet of paper. That is no problem, it's simply a passage that leads off the map. for the other dice, I mark their locations as circles, and then draw thick black lines to connect them. As can easily be seen, there is not much going on on the map yet, but we can toss more dice, for smaller parts of the cave system.

Step 4: Smaller caves

The first set of smaller caves lands mostly around the big lake I took creative liberty of creating in step one (such features are usually added much later in the process), which kind of makes sense. But also note the one die off the map where two of the waterways confluence (or split? We don't know. Yet.); there will be something there as well. But next, we add some more caves.

Step 5: Even more smaller caves

The second set of smaller caves goes partly off the map, and lands close to already-existing features. No problem, those clusters will build natural settled centers (or an amassment of dangers)

Step 6: More caves, and more tunnels leading off the map

With this done, we have a map populated with a bunch of water bodies, some larger and smaller caves; but we don't know yet which is which. Luckily, the chthonic contents table helps figring out what is where.  Before we get to that though, let's add some markers to the previously created cave system that allow a referee to discern how long it takes you to get from one main point to another.

Step 7: marking off segments

 A nice feature of the marks is that they abstract away distances as absolutes; they're more about how much time it takes to get from one mark to the other. In this example, assuming every mark is three hours of travel means you can get around the north-bend near the lake in about 12 hours, but traveling between the two larger nexuses in the south west quadrant, even though they are much closer in absolute distance, takes you 18 hours! This should give you ideas about how difficult the terrain is to cross, for whatever reasons. Paolo used differently colored marks in his pictorial example to allow for different travel time segments, but I simply stuck with one.

I did mess up here a bit and instead of setting every mark at 1d6cm from the previous one, I actually rolled a d6 for the number of marks. This made for a somewhat more dynamic map with a somewhat bounded maximum travel distance, but it also caused quite the crowding in the bottom. This would bite me in later steps. I did consider going back to step 6 and redo the marks, but then this gave me a natural center of activity among the caves I created.

All that's left now is rolling for every mark whether something of note is to be found there (50% chance) and what it is. You do this with the Chthonic Contents table, which generates a mix of natural features (such as mires or waterfalls), settlements (such as monasteries, goat villages, or magical schools) and magical or mysterious elements (such as mana-tar seams, altars or mysteric secret places).

Some of these features have their own sub tables to further develop their nature, size, state of (dis)repair, so if you work through this you will have your own but very hypogean pointcrawl map. These features are sometimes hidden, so they may not be marked on any of the official maps, but they may be known to some people, or are ripe for discovery by the players.

The map that you created this way should help you identify some interesting places. As the text explains, if some features that don't seem to fit well end up close to each other, make them work. Don't take the map created this way as unchangeable gospel either; rather assume it to be the starting point and allow the actions of your group to change any feature as they are wont to do. Just hope they don't flood everything with lava.

In  a follow-up post I will look at the fully fleshed-out map and discuss some of the additional reasons why the CHTHONOTRON is a good tool in the aspiring referee's toolbox.