What Is Procedural Generation and How Do You Use It to Make TTRPG Maps?
Procedural generation ("procgen") means a program builds a map from rules and a random seed rather than you drawing every wall and river by hand. For tabletop RPGs it is most useful when you need a location fast — a village the party just decided to visit, a dungeon for tonight's session, or a whole realm for a sandbox campaign. Watabou's Procgen Arcana (watabou.github.io) is a free browser-based set of generators that covers exactly these cases: its landing page presents a choice of Realm, City, Village, Cave/Glade, and Dungeon (plus Dwelling). You pick a card, the generator produces a map, and you can reroll until something fits.
How procedural generation differs from hand-drawn maps
A hand-drawn map is authored: every decision is yours, and the result matches your mental image exactly. A procedural map is sampled: the generator applies consistent rules (coastlines, road networks, building placement, room connectivity) and a seed determines the specific outcome. That trade-off matters:
- Speed — a usable map appears in seconds, not an evening.
- Variety — rerolling gives you options you would not have thought to draw.
- Less control — you get a plausible result, not a specific one. If a plot point depends on a particular layout, you may still need to draw or edit it.
- Consistency — the same seed reproduces the same map, so you can keep a result you like and return to it.
What each generator produces
The site organizes its tools as cards you choose from. Based on the available options:
| Generator | Typical use at the table |
|---|---|
| Realm | Regional/nation-scale maps for campaign geography and travel |
| City | Urban locations with streets and districts |
| Village | Small settlements the party passes through or settles in |
| Cave/Glade | Small wilderness or subterranean encounter sites |
| Dungeon | Multi-room interiors for exploration and combat |
| Dwelling | Individual buildings and interiors |
Pick the scale that matches the decision your players are about to make. A "where do we go next?" moment calls for a Realm or City map; "what's behind this door?" calls for a Dungeon or Dwelling.
Generating a map step by step
- Open the site at watabou.github.io and choose the card for the scale you need (for example, Village).
- Let it generate. The tool renders a complete map immediately — you do not start from a blank canvas.
- Reroll or adjust. If the result does not fit, generate again. Most Watabou tools expose parameters (size, density, and similar) alongside the reroll control, so you can steer the output rather than only re-rolling blindly.
- Note the seed if the tool exposes one. A seed is what makes a result reproducible; if you want the same map next week, record it.
- Export or save. Use the tool's export/save option to keep the map as an image or file for your notes, VTT, or printout.
Expected result: a finished, labeled map you can drop into a session without further drawing.
Common snags
- The map is plausible but wrong for your story. Reroll a few times before giving up on the generator; if a specific feature is required, treat the generated map as a base and annotate it.
- You lost a map you liked. If you did not save the seed or export the image, you cannot reliably get it back — export as soon as a result works.
- Scale mismatch. A Realm map will not give you room-by-room detail, and a Dungeon map will not show where the dungeon sits in the world. Generate at two scales if you need both.
When to generate and when to draw
Use a generator when the location is improvised, background, or one of many — travel stops, a city the party is passing through, a dungeon you need for tonight. Draw (or hand-edit a generated map) when the location is the focus of play: a home base with named NPCs in specific buildings, a puzzle dungeon whose solution depends on exact geometry, or anything your players will revisit and map themselves. A practical middle path is to generate, then relabel rooms and move a few features so the map matches your notes.