The world of Ystoir is not endless: it is a square of 16 384 blocks a side (1 block is 1 metre), centred on the origin, from height -256 to 1024, with the sea at height 0. Its whole map is decided when the world is created, and the land is an archipelago surrounded by open sea.
The archipelago
North is toward negative Z, east toward positive X. Five large islands make up the land:
| Island | Position | Relief |
|---|---|---|
| Mitan | the centre, about 4.7 km across | few mountains |
| Aube | east (around X 4500) | many mountain chains |
| Vepre | west (around X -4500) | few mountains |
| Givre | north (around Z -4600) | the most mountainous island |
| Cendree | south (around Z 4550) | the fewest mountains |
Between them:
- Four main straits join the Mitan to each outer island, at least 600 m wide. Small rocky islets (18 to 30 m) stand across each strait every 150 to 300 m, close enough to cross from rock to rock.
- Four diagonal passages, at least 1.3 km wide, separate the outer islands from each other, with no islets.
- The Dents: off the outer coasts of Aube, Vepre, Givre and Cendree, 6 to 9 chains of small rocky islets (4 to 11 each, 5 to 22 m high) run along the shore.
- Every island has headlands, inlets and groups of little islets just off its coasts.
- A band of open sea 1500 m wide runs along the edge of the world, its floor sinking to 200 m deep. There is no land past it.
The sea floor drops to a shelf about 20 m deep within 300 m of the coasts, then to about 70 m in the open sea. Inland, hills rise up to about 90 m and mountain chains up to 800 m. Rivers (up to 40 m wide and 6 m deep) and lakes drain the islands.
Climate
Each place has a temperature and a humidity, fixed with the map:
- The temperature goes from -12 degrees at the northern edge to 28 degrees at the southern edge, and falls 6.5 degrees per kilometre of height. Givre is the coldest island, Cendree the warmest.
- The coasts are wetter than the inland. Vepre is the most humid island, Cendree the driest (with a wetter corner in its south east and a hotter one in its east), the Mitan a little dry.
The seasons swing the temperature through the year on top of this (see Seasons and weather), but the biomes stay where the map put them.
How a biome is chosen
Each spot of the map takes the biome of highest priority whose conditions it meets. Height is metres above sea level, temperature in degrees, humidity from 0 (dry) to 1 (wet).
| Biome | Conditions | Priority |
|---|---|---|
| Ocean | below -3 m | 100 |
| Beach | -3 to 3 m, 2 degrees or warmer | 90 |
| Stony shore | -3 to 3 m (the colder coasts) | 85 |
| Snowy peaks | above 300 m, -6 degrees or colder | 80 |
| Mountains | above 450 m | 70 |
| Tundra | -2 degrees or colder | 50 |
| Swamp | 0 to 60 m, humidity 0.75 or more, 8 degrees or warmer | 45 |
| Forest | 4 to 18 degrees, humidity 0.58 or more | 40 |
| Taiga | -2 to 4 degrees, humidity 0.35 or more | 40 |
| Steppe | humidity 0.3 or less, 4 degrees or warmer | 30 |
| Plains | everywhere else | 0 |
The biomes
Ocean, beach and stony shore
- Ocean: a sand floor. Herring and cod swim there; nothing grows.
- Beach: sand over sand.
Loose Stones and, over
limestone or sandstone, 
Loose Flint; 
Mugwort,
Mandrake (Mitan and Cendree only) and 
Water Lily. Crabs, birds,
and the drowned at night. - Stony shore: gravel. Loose stones are common here, flint too. Wild
cabbage, Mugwort and
Weld. Crabs, and the
drowned at night.
Plains and steppe
- Plains: grass over dirt, which is
Black Earth on the
Mitan and 
Volcanic Ash on Cendree. Scattered groves of oak, birch, ash, rowan and
wild apple (beech in Aube, chestnut in the Mitan, pine in Cendree), willows and alders by the
water. Tall grass, poppies, cornflowers, reeds, 
Native Copper on river and lake
banks. Wild wheat, flax,
onion and carrot; madder, weld, nettle, bramble,
St John’s wort, woad (Aube and the Mitan), heather (Givre and the Dents). Horses, sheep, rabbits,
rooks, chickens, asp vipers; aurochs on the Mitan and Cendree. - Steppe: grass over the same soils, very few trees (oak; pine in Cendree). More loose stones and flint than the plains. Wild barley, oats, hemp and garlic; mugwort, madder, weld, St John’s wort. Horses, goats, rabbits, asp vipers; aurochs on the Mitan and Cendree.
Forest, swamp and taiga
- Forest: grass over dirt (volcanic ash on Cendree). Oak, birch and ash,
with yew, rowan and wild apple; beech woods on Aube, ash and chestnut on the Mitan, pine on
Cendree. Ferns, mushrooms, bushes,
Dead Branch under the trees, native copper on
the banks. Wild peas, broad beans and
grapes; bilberry, bramble, ceps, chanterelles, wild garlic, nettle,
moss, mistletoe in the trees, belladonna. Deer, boars, foxes, rabbits, wolves, lynxes, bears;
elk on Vepre. - Swamp: grass over dirt, dirt under the water. Alder, willow, ash and
oak, dense reeds. Wild hops, cranberries, moss, nettle. Just under the
surface,
Peat beds and 
Bog Iron Ore (on Vepre, Givre and
Cendree, not on the Mitan nor Aube). Boars, birds, and ghouls at night. - Taiga: grass over
Podzol. Spruce, with birch and rowan.
Wild rye and turnip; bilberry, cranberry, heather,
ceps, chanterelles, aconite, moss; peat on Vepre, Givre and Cendree. Deer, wolves, foxes, lynxes, bears; elk on
Vepre.
Tundra, mountains and snowy peaks
- Tundra: snow over dirt, no trees. Loose stones, native copper on the banks, peat on Vepre, Givre and Cendree. White wolves, arctic foxes, spiders.
- Mountains: bare stone, gravel under the water. Plenty of loose stones,
Aconite, 
Lichen, moss. Goats and bears outside; bats, rats and
weavers in the caves. - Snowy peaks: snow over stone. Loose stones only. White wolves and arctic foxes, few of them.
Rocks and ores by island
The rock under the soil, and so the ores, depend on the island. An island’s underground runs on under its shores and islets.
| Island | Main rocks | Ores found there |
|---|---|---|
| Mitan | sandstone and limestone | coal (rich), iron, flint, rock salt (only here), a little galena, jet, fire clay |
| Aube | granite and andesite, slate in the north | copper, tin, gold, quartz (all rich), iron, magnetite |
| Vepre | thick limestone over sediments | coal, iron, galena, bog iron (all rich), flint, peat, jet, fire clay |
| Givre | granite, slate, andesite, some basalt | iron, gold, copper, peat, a little tin, quartz, magnetite, bog iron |
| Cendree | sediments in the west, basalt in the east | copper, iron, magnetite (rich), flint, peat, bog iron |
Clay lies in pockets just under the soil where the land is humid.
Finding things
- Flint for your first tools: beaches, stony shores and steppe over limestone or sandstone.
- Native copper: river and lake banks of the plains, steppe, forest, taiga, swamp, tundra and mountains.
- Wood: the forests and the taiga; the plains have only scattered groves, the steppe almost none.
- Fertile soil: the black earth of the Mitan and the volcanic ash of Cendree.
- Metals: tin is on Aube (a little on Givre), galena mostly on Vepre, rock salt only on the Mitan.
See Tools and mining for the ores, Herbalism for the wild plants, Farming for the wild crops and Creatures and combat for the animals.