Status of the project: Finished, source code available, but the project is inactive. Making the map paintable also meant I needed to make it fast. Maybe in a future version also let you paint the biomes. I wanted to generate something (mountains, valleys, oceans), then let you change those things, and then generate the rest (biomes, rivers). With procedural generation we usually let the system generate everything. Being able to paint your own features on the map.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. 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. Download high resolution image (doesn’t work on all platforms). Everything you create with it is yours to do with as you please.

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. Play with the sliders to change the simulation and style.