Pick a starting seed, then paint mountains, valleys, and oceans on the map! It will simulate evaporation, wind, and rainfall to determine biomes and rivers.

Ocean Water Valley Mountain Reset

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Play with the sliders to change the simulation and style. For example, try decreasing raininess slider to see how reducing rainfall will make rivers dry up, or try decreasing lg_min_flow to see more small streams.

Treat this as a tool. Everything you create with it is yours to do with as you please. Credit is appreciated but not required. Suggested tag: #mapgen4 . Download a high resolution version:

Chrome/desktop, Safari/desktop, Safari mobile: Download

Chrome/mobile, Firefox/mobile, Firefox/desktop: I haven’t gotten this to work (also see[1])

Goals for this project:

A hand-drawn inspired look. If you look at maps from Lord of the Rings and other fantasy settings, you’ll see the rivers and coastlines are top-down but the mountains and trees are side view. The map above is rendered in full 3D (try the rotate_deg and tilt_deg sliders!) but I used a custom projection and outline to more closely match a hand-drawn map.

Being able to paint your own features on the map. With procedural generation we usually let the system generate everything. I wanted to generate something (mountains, valleys, oceans), then let you change those things, and then generate the rest (biomes, rivers). Maybe in a future version also let you paint the biomes. Making the map paintable also meant I needed to make it fast.

Status of the project: Finished for now. I have a series of blog posts[2] about how I made these maps:

Also see my project from 2010[14], where I started developing these techniques. I have a long list of things I’d like to add, but I’m not actively working on them. I’d like to improve the UI, and also add trees, more biomes, towns, seasons, nations, watersheds, and lots more. Someday.