Open source, free to use
Build a world from the ground up.
Terrain, rivers, climate and borders. A world shaped by geography, starting with a seed.
Free · Open source · Runs locally
How a world is made
Plates and mountains
Drifting plates collide, and what they build depends on what meets: coastal ranges with volcanoes behind them, broad plateaus, island arcs, rift valleys that flood into chains of gulfs.
Erosion
Slopes collapse, rivers cut valleys and carry the debris down to floodplains, fans and deltas. Basins drain through the notches their overflow cuts.
Seas and ice
Continental shelves along the coasts; glaciers in cold mountains and scoured lake country under old ice sheets.
Climate
A warm season and a cold one, ocean currents, continental interiors, monsoons and rain shadows. Biomes follow the Köppen rules, so deserts sit where deserts sit.
Rivers and lakes
Water runs downhill to the sea or into lakes. Dry basins hold only the water their catchment can keep against evaporation, so an inland sea shrinks to a salt lake.
Realms and peoples
Borders follow watersheds, rivers and coasts. Peoples spread through country that resembles their homeland, so cultures cross borders the way real ones do.
Features
- Views
- Fifteen: the fantasy map, political and peoples, elevation, biomes, temperature and rainfall by season, plates, currents, winds.
- Styles
- Twelve for the map: atlas, vellum, ink wash, nautical chart, pen and ink, Mars, natural, and a colour-blind-safe palette.
- Themes
- Sixteen for the window: light, dark, high contrast, colour-blind, and styled sets from Nautical to Lemon Blueberry.
- Editing
- Every generated name and border can be overridden, and the overrides are kept with the world.
- Saves
- A save holds the finished world, and the same file opens in the browser and on the desktop.
- Export
- PNG, WebP or JPEG, up to 4096 × 4096; or the data behind the map: a 16-bit heightmap with its metre scale, and biome and realm index maps with their legends.
- Resolution
- 512 to 4096 cells across; the browser starts at 512, the desktop app at 1024.
- Acceleration
- Optional, for erosion and export rendering: WebGPU in the browser, OpenGL on the desktop.
Notes
Running it in a browser
Recent Chrome, Edge, Firefox or Safari. The first visit downloads about 4.5 MB and is cached after that; nothing you make is uploaded anywhere.
The optional graphics-card acceleration uses WebGPU where the browser offers it.
Sizes, formats and speed
An export re-runs the whole pipeline at the size you ask for rather than enlarging what is on screen, so the detail is real; 4096 wants a few gigabytes, which is why the browser stops at 2048 on a phone.
WebP is about a quarter of PNG's size and softens thin rivers and borders very slightly. With a graphics card, a 1024 world takes about twenty seconds on a 2026 phone and 2048 about a minute and a half.
The Atlas is a work in progress
Today it lists a world's realms and landmarks, lets you rename them and place labels, and stops there. A full atlas is planned for a later release, targeting 4.0: named continents, seas, bays, straits and ranges, with labels set out the way a printed map sets them. Names you give now are kept with the world.
Desktop versionWindows
Bigger worlds, more threads and no download before you start. Portable zip or installer. The installer is unsigned, so Windows shows a SmartScreen warning the first time; choose “More info”, then “Run anyway”.
Get the latest release ↗