Seed 42 · 500 × 1000 km · v1.0

Every world
begins with
a single number.

Arda grows a continent from one seed: plates and mountains, wind and rain, rivers that find the sea, realms, towns and roads. Then it takes you all the way down to the five-foot square where your players stand.

Forge your first world Walk through one

arda generate --seed 42 --micro --out worlds/w42

Atlas overview of a full-size generated continent: snow-capped ranges, green lowlands, roads and settlements in a deep blue sea — 500 × 1000 km · seed 42 · Atlas

The descent

From a thousand kilometres to five feet, without a seam.

One saved world answers at every scale. Zoom in and nothing is invented on the spot that contradicts what was above it.

1 KM GRID Continent & realms Tectonic relief, climate by latitude, realms with borders and roads.
100 M CELLS Areas 51.2 km tiles of eroded terrain, rainfall, rivers and lakes.
TOWN PLANS Settlements Towns sized by their land, with fields, districts and history.
5 FT SQUARES Battle maps 64 × 64 squares with walls, cover and difficult terrain.

Showcase · straight from the generator

Places nobody drew.

Every map below was rendered by Arda 1.0 from a seed. No hand edits. The market, the docks and the cave all sit somewhere real in a generated world.

City market square with coloured stalls, cobbles and walled gardens — **City market**cell 546, 658 · 64 × 64 squares

Dense forest canopy over a rocky hillside — **Forest on a steep slope**cell 716, 1423

Manor house interior with rooms, furniture and partition walls — **Manor interior**stone partitions, great hall

Wooden docks with moored boats on deep water — **Port docks**cell 544, 657 · moored boats

Sandy beach between grassland and dark sea — **Coast and beach**cell 778, 751

Edge of a town giving way to strip fields and a river — **Town edge and strip fields**3 × 3 cells, seamless

Village houses with crofts, gardens and dirt yards — **Village crofts**cell 537, 796 · kitchen gardens

Snowfield broken by rocky ribs and boulders — **Snowbound crag**cold world · cliff ribs

Dungeon of stone rooms and corridors — **Dungeon level**seed 7 · loops and secret doors

Winding cave with pools of water — **Natural cave**seed 7 · pools and streams

How it works

Geology first. Then water. Then people.

Arda builds a world the way a world is built: each layer only uses what the layer beneath it already settled.

Seed and shapeA seed and an extent fix everything. Plates collide into ranges; winds by latitude carry the rain.
Weather the landHillslopes diffuse, glaciers carve troughs, and erosion runs across area edges so no seam becomes a wall.
Let the water find its wayConnected drainage and an annual water balance: lakes only where there is a basin and the rain to fill it.
Settle itTowns where the land can feed them, ports where ships can reach, roads with grade limits, balanced realms.
Give it a pastNamed events, causal histories, notables and a gazetteer of seas, capes, forests and ranges.
Serve every scaleAtlas and political maps up to 32K, JSON, and battle maps on demand from a frozen /v1 HTTP API.

DeterministicSame seed, same configuration, same generator: the same world, byte for byte. CI checks a golden world on Linux, macOS and Windows.

Saved, not re-rolledThe world is written once as binary layers. Every map and export reads it back; higher resolution never changes the land.

Built for the tableBattle maps follow one rules contract: walls block, stones are difficult terrain, torchlight stops at walls.

Tutorial · about ten minutes

Your first world, start to battle map.

Five steps take you from nothing to a populated continent and a five-foot grid you can drop into a VTT. Start with MICRO: eight areas, 102 × 204 km, ready in seconds.

Drop --micro for a full 500 × 1000 km continent, or pick your own with --size 300x600. Full reference in the README.

Town edge with strip fields and a river, as a tactical map

Install Grab a prebuilt binary from Releases (Linux, macOS, Windows), pull the Docker image, or build from source with stable Rust.
```
git clone https://github.com/DiceMasterIO/arda.git
cd arda
cargo install --path crates/arda-cli --locked
```
Generate the land Relief, climate, erosion, rivers and lakes, saved as binary layers under worlds/w42/.
```
arda generate --seed 42 --micro --out worlds/w42
```
Settle it Towns, roads, realms and names; then town plans, politics, history and notables.
```
arda settle --world worlds/w42
arda society build --world worlds/w42
```

Draw the maps An Atlas overview, a political map, or any area at up to 32K.

arda export --world worlds/w42 --overview --style atlas --out maps
arda export --world worlds/w42 --overview --style atlas --society political --out maps/political
arda export --world worlds/w42 --area 1,1 --style atlas --quality 16k --out maps

Serve it and step inside Start the read-only server, then ask for the battle map of any 100 m cell.

arda-server --world worlds/w42
curl -o market.png http://127.0.0.1:8787/v1/tactical/cell/546/658.png

And below it all

Dungeons and caves, on the same grid.

Rooms with loops, locked and secret doors, stairs and torchlight; natural caverns with pools and streams. One command, one seed.

arda dungeon --seed 7 --kind cave --out cave.json --render cave.png

Dungeon level: stone rooms joined by corridors

Natural cave with pools and a winding outline

Pick a number.
Find out what lives there.

Arda is free and open source under Apache-2.0. Prebuilt for Linux, macOS and Windows, or as a container.

Download Arda 1.0 Star on GitHub

docker pull ghcr.io/dicemasterio/arda:1.0.0

Every worldbegins witha single number.