What Is Procgen and How Is It Used to Generate Maps for TTRPGs?
Procgen (procedural generation) is the use of algorithms plus controlled randomness to produce content automatically instead of drawing it by hand. In tabletop RPGs and worldbuilding, it is most often used to spin up maps — realms, cities, villages, caves/glades, and dungeons — in seconds, so a game master can drop a location into play without hours of cartography. It fits best when you need a plausible map fast and can accept that the details are generated rather than authored; it fits poorly when a specific room, street layout, or political border must match a fixed story beat.
How procedural generation actually works
A procgen tool takes a small set of inputs (map type, size, seed, density, and similar settings), runs them through rules and randomized steps, and outputs a finished map image or file. The randomness is not pure chaos — it is constrained by the algorithm, which is why the results look like coherent settlements or cave systems rather than noise.
Two ideas explain most of the behavior:
- Seed: the starting value for the random process. The same seed with the same settings reproduces the same map; a new seed gives a new one. This is what makes results shareable and repeatable.
- Constraints/rules: the logic that keeps output believable — buildings stay on land, roads connect settlements, dungeon corridors connect rooms.
For example, if you generate a village and the well ends up in an odd spot, changing the seed usually reshuffles the whole layout, while tweaking a setting (like settlement size) changes it in a more directed way.
What procgen maps are used for in TTRPGs and worldbuilding
The typical uses map directly onto the location types these generators offer:
| Map type | Typical use at the table |
|---|---|
| Realm | Regional/world overview for a campaign setting |
| City | Urban adventure hub, districts, travel between locations |
| Village | Starting town, rest stop, small-scale social encounters |
| Cave/Glade | Wilderness encounter site, hidden grove, small cave |
| Dungeon | Delve site for combat, exploration, and treasure |
A game master can generate a village when players unexpectedly travel off the prepared path, or build a whole realm to sketch a world before writing any lore. Worldbuilders use the same output as a visual base for naming places and inventing history.
Procgen vs. hand-drawn maps: which to choose
Both approaches produce usable maps; the right choice depends on your constraints.
- Choose procgen when: you need speed, you need many maps (a region full of villages), you want inspiration from an unexpected layout, or the location is background rather than a set piece.
- Choose hand-drawn when: the map must match a precise narrative (a specific throne room, an exact border), you need a consistent art style across a published product, or the layout itself is a puzzle the players must solve.
A common hybrid: generate a map to get a plausible structure, then hand-edit labels, key rooms, and story-relevant details.
The general workflow for using a generator
The steps are consistent across most tools, including the generators on Watabou's Procgen Arcana, whose landing page presents a simple "Pick a card..." choice among Realm, City, Village, Cave/Glade, and Dungeon.
- Pick the map type that matches the scale you need (realm for regions, city/village for settlements, cave/glade or dungeon for adventure sites).
- Set the parameters the tool exposes — size, density, seed, and similar options. Start with defaults if you are unsure.
- Generate and review. If the layout does not fit, either reroll (new seed) or adjust a setting.
- Export or save the result in whatever format the tool provides, then bring it to your VTT, notes, or print.
- Add your own layer: names, hooks, factions, and the specific encounters that make the location matter.
Verification: the quickest check is whether the map is internally consistent — roads reach buildings, rooms connect, terrain makes sense. If it is, it is ready to use or annotate.
Common limitations to plan around
- Random details may not fit your story. A generated city will not know that the thieves' guild must be near the docks; you place that yourself.
- Rerolling changes everything. Because a new seed regenerates the whole map, fine-tuning one detail often means accepting a new overall layout.
- Consistency across maps is not guaranteed. A village and a city generated separately may not share a coherent geography unless the tool links them.
- Detail level varies by type. Settlement and dungeon maps tend to carry more usable structure than broad realm maps, which are better as overviews.
Treat procgen output as a strong first draft: fast, varied, and good enough to run a session, with the understanding that story-critical specifics still come from you.