Generating Maps for Heart: The City Beneath

09 Jul, 2025

Johann Jacob Dillenius. Detail from "C. fontinalis" in Historia muscorum. 1741.

I'm gearing up to play a campaign of Heart: The City Beneath with our micro-campaign group. This'll be an interesting stretch for us. The game is much more of a storygame than our usual pOSR fare.

Heart is really structured around delves between a set of pre-written landmarks. The routes between those landmarks may shift and change, but to some degree transit between various settlements and sites is possible. The games authors' actively discourage the GM from just making a concrete map from the beginning, instead suggesting that you pull a bit of a "quantum troll" and surface just the right location at just the right time. I use that term without disparaging - it seems like a totally reasonable way to structure your campaign.

That said, I'm not doing that. I'm going to make a schematic map of the relative positions of all the landmarks we'll be using. I'll start with some canon connections that may shift and change in response to PCs actions or time passing. I do this for two reasons:

1. I find it easier to prep this way. I can read up on the landmarks that are in reasonable travel distance each session. If the PCs ask to go somewhere far away or research how to get somewhere, I can give them concrete answers.
2. As Quinns helpfully recapitulated in his recent Mythic Bastionland review, I subscribe to the idea that travel sequences without enough choices aren't interesting - too little info or too much info both turn it into bookkeeping.

I won't share the entire map with the players, but I'll give them a smattering of info to start and let them ask around in settlements for more.

Creating the Map

Now I could just exercise GM fiat and select my favorite landscapes and thread them together, but honestly, its easier for me to make a procedure and follow it. Towards that end, I propose the following steps:

1. Randomize a list of landmarks.
2. Throw dice to determine landmark locations.
3. Thread paths between landmarks.
4. Zhuzh a little.

We'll repeat these steps for each of the three tiers with meaningful landmarks - 1, 2, an 3. If you have read so far and aren't familiar with Heart, the tiers are basically danger levels. Tier 1 is basically livable if a little weird, Tier 2 is a constantly shifting roil of unlikely spaces, and in Tier 3 you have no reasonable expectation that the laws of physics will apply the same way from one room to the next.

Randomize a List of Landmarks

How many landmarks per tier? I don't know exactly, but something like d6 + 6 feels about right.

For our actual Heart game, I plan to use the list of landmarks in the book. I'll take each tier's landmarks and toss them into a list randomizer.

I don't want to spoil that list for my players though, so here's a whole bonus generator mid article!

Generating Heart Landmarks

We can make a list of landmarks using the three tables below. For each domain:

1. Flip a coin, if heads the landmark has one domain; tails, two.
2. Roll d8 for each domain to determine its type.
3. Roll d8 for an adjective and noun. If two domains, use the first for the adjective and the second for the noun.

Domain Type

Adjective

Noun

So, for our example, we end up with the following list of 9 landmarks:

1. Ashen Tunnel (Desolate / Warren)
2. Labyrinthine Hole (Warren)
3. Stalwart Refuge (Haven)
4. Verdant Tangle (Wild)
5. Bloody Ruin (Cursed / Desolate)
6. Sloughing Vent (Cursed / Warren)
7. Spireblack Relay (Technology)
8. Glyph-etched Tongue (Occult / Cursed)
9. Esoteric Outpost (Occult / Haven)

Throw Dice to Determine Landmark Locations

Our goal is to set up something like an exquisite corpse here, with each tier filling a page and linking both up and down.

To start, cast Nd6 onto your page where N is the number of landmarks in your list. Set aside any that fall off the page for now but try to preserve its result.

Then, working from top to bottom, lift each die and right the first unused entry from your list of landmarks, then note the die result. At this phase I inevitably nudge a few dice here and there. That's fine and maybe even desirable. I want about a finger tip worth of distance minimum between nodes in most cases.

Working through this process I ended up with the following:

Thread Paths Between Landmarks

So how do we connect paths? Again, let's start from the top.

We should have a number of paths connecting down to this Tier. If you are in Tier 1, then let's say that Tier 0 (the surface or near to it) connects to our first d2+1 landmarks. Draw these paths in as vertical arrows that terminate at their destination.

Now, working from top to bottom, convert your d6 result into a d3 (so divide by 2 and round up). This is how many paths should connect to this landmark, ignoring paths down from a higher tier.

• If the current site doesn't have enough yet, draw new paths to the nearest other sites that haven't hit their threshold yet.
• If there are no such landmarks, draw a path going down to the next Tier. Again, this will be a vertical arrow, but with the tip pointing away from the landmark.

You should end up with something like this:

Zhuzh a Little

As our final pass, we'll add some character to our map and adjust for some oddities.

If you have two (or more) disconnected systems of paths, find the two landmarks where those systems are closest. Connect them with a hazardous path, indicated with an exclamation mark or a little skull. This route will be extra difficult to traverse.

If the map feels not networked enough, with too many dead ends or too clear a route down to the next tier, add some secret paths, indicated with a question mark or a little eye. These are lesser known routes that local leaders might be willing to provide info on for a price.

If you have dice that fell off the map during step 2, place them somewhere remote with no connections. Path these together in the same way you connected the rest of the map. The routes to these landmarks are unknown. If you can't navigate to this region by coming up from a lower tier, only the Heart can lead delvers to these landmarks.

Is this map Tier 1? Make sure at least 1/3rd of your landmarks are havens to make this area feel more hospitable. If you are short, add the haven domain to landmarks until you do, working in order of highest roll, breaking ties towards higher locations.

Have only one path downwards? Add another, stemming from the next lowest landmark that isn't directly above your previous path downwards.

So at the end of our process, my Tier 1 looked like this:

Using the Map

Without going into too much detail on Hearts' rules, this map offers some nice features. First, the domain tags make it easy to construct delves between the landmarks. Just mix the terms from the start and the destination. What happens when the biomes these terms suggest overlap?

Second, It feels reasonably interesting to make choices about which route to take. Let's say you are in the Ashen Tunnel and you need to get to the Spireblack Relay. Do you risk the tough journey through from Verdant Tangle to Sloughing Vent or double back up to Tier 0 and return via Stalwart Refuge. As with any pointcrawl, there aren't a paralyzing number of possible options.

Third, the spatial information here gives us all kind of juicy details to riff off of in our prep or play. The secret route from Stalwart efuge to Glyph-Etched Tongue feels loooong. Why would you need to use it? Verdant Tangle and Sloughing Vent are so-close together that their biomes basically touch. Labyrinthine Hole, Ashen Tunnel, and Verdant Tangle really feel like their own island. One imagines that anyone living out there only scarcely sees someone from the more populous Bloody Ruin, let alone the rumored Esoteric Outpost...

I'll admit that the final steps here are a bit loose. In practice, the generative steps of casting dice and drawing the connections are the most important. From there, I more or less just suggest "make it work!" You have a better sense of what you want out of your subterranean hellscape than I do. Don't fret about bending the procedure here and there if something just makes sense.

#Heart #generators #practice