World generation

Basics Menus Game Creation Gameplay Pawns Plants Resources Gear Mods Game Creation Scenario system AI Storytellers World Generation Biomes

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Worlds in RimWorld are generated from either random or user-provided seeds that allow for a completely new experience every time. Each world is uniquely filled with multiple biomes that change what the world looks like and how it behaves. For example, some biomes feature a large amount of mountains, while others are full of grasslands.

As of version 0.16.1393 (21 December 2016) Part of the world system's overhaul includes sliders for overall planet temperature and overall rainfall, with the result of changing them being true to what would happen in real life. Time zones are also modelled as the world actually physically exists and is fully interactive. Temperatures in regards to proximity from the equator are also correct; with hotter biomes being more central and colder biomes being closer to the poles.

In Alpha 17, when reloading the world after opening the colony, the game now shows a loading screen.

Generation process

Basics Menus Game Creation Gameplay Pawns Plants Resources Gear Mods Game Creation Scenario system AI Storytellers World Generation Biomes

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Biomes are types of area on a planet, characterized by their terrain properties, climate, flora and fauna, diseases and special challenges. Each world tile has one particular biome. There are twelve playable biomes types in RimWorld, which can be divided into three categories: Warm, Hot and Cold. Oceans and lakes appear as world tiles but are not playable biomes.

The following is a simple summary of the biomes by difficulty, overall cold biomes are more challenging than their hot counterparts.

Warm biomes

These biomes are rich in flora and fauna, and also have a slightly elevated rate of disease. They generally have year-round growing periods, or longer growing periods at the very least. Traveling speed is fast in normal forests and average in dense forests but slow in marshes and during cold seasons if they have one.

Temperate forest

Forests of deciduous trees interspersed with fertile clearings. Many species of animals move around among the trees and on the plains.

Temperate Forest

Growing season, temperature, travel and disease

• Growing Season: From all year to 20/60 days.
• Average Temperature: 25 °C (77 °F) to 0 °C (32 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to -25 °C (-13 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, but sometimes 3 due to winter.
• Forageability: 100%.
• Grazable: Only during growing season.
• Disease frequency: 1.2 per year.

Flora

Berry bush, Brambles, Bush, Dandelions, Grass, Oak tree, Poplar tree, Tall grass, Wild healroot, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Alpaca, Bison, Boomalope, Boomrat, Cougar, Deer, Donkey, Gazelle, Grizzly bear, Guinea pig, Hare, Horse, Ibex, Lynx, Megasloth, Muffalo, Raccoon, Rat, Red fox, Rhinoceros, Squirrel, Timber wolf, Tortoise, Turkey, Warg, Wild boar, Yak

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Temperate swamp

Wetlands choked with vegetation and disease. Dense overgrowth makes it hard to move around, and clearing areas for building takes a long time. Much of the terrain is too marshy to support heavy structures.

A more wet version of the Temperate Forest. Like in all swamps, diseases are more common. The marshy soil will probably require bridges before constructing buildings and the terrain is really slow to travel, but this biome also has more fertile soil.

Temperate Swamp

Growing season, temperature, travel and disease

• Growing Season: From all year to 20/60 days.
• Average Temperature: 25 °C (77 °F) to 0 °C (32 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to -25 °C (-13 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 4, but sometimes 6 due to winter.
• Forageability: 75%.
• Grazable: Only during growing season.
• Disease frequency: 1.5 per year.

Flora

Berry bush, Bush, Chokevine, Cypress tree, Maple tree, Tall grass, Wild healroot, Willow tree, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Alpaca, Boomalope, Boomrat, Cougar, Deer, Grizzly bear, Guinea pig, Hare, Horse, Ibex, Lynx, Megasloth, Muffalo, Raccoon, Rat, Red fox, Rhinoceros, Squirrel, Timber wolf, Tortoise, Turkey, Warg, Wild boar, Yak

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Tropical rainforest

A thick, moist jungle, buzzing with animal life and infested with disease. Despite its visual beauty, this is a very dangerous biome. Choking overgrowth, aggressive animals, and constant sickness are why some explorers call this the "green hell".

Tropical Rainforests are famous for having many diseases, including Sleeping Sickness: a slow-progressing, long-lasting disease that is exclusive to the tropics. Many trees make it difficult to clear land and rapid plant growth makes it difficult to keep it clear.

Tropical Rainforest

Growing season, temperature, travel and disease

• Growing Season: From all year to 40/60 days.
• Average Temperature: 30 °C (86 °F) to 15 °C (59 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to 0 °C (32 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 2, rarely 4 due to winter.
• Forageability: 100%.
• Grazable: Most of the time, during growing season.
• Disease frequency: 1.7 per year.

Flora

Alocasia, Bamboo tree, Berry bush, Bush, Cecropia tree, Clivia, Giant rafflesia, Grass, Low shrubs, Palm tree, Tall grass, Teak tree, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Alpaca, Boomalope, Capybara, Cassowary, Chinchilla, Cobra, Elephant, Guinea pig, Monkey, Panther, Rat, Rhinoceros, Tortoise, Wild boar

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Tropical swamp

A plant-choked, steamy swamp seething with parasites and pathogens. Much of the land is too marshy to build on. Difficult movement, aggressive animals, and rampant disease make living here a nightmare.

A more wet version of the Tropical Rainforest. Like in all swamps diseases are more common. The marshy soil will probably require bridges before constructing buildings and the terrain is really slow to travel, but this biome also has more fertile soil. Diseases are even more constant here than in Tropical Rainforests, so making a proper hospital and having good doctors is a priority.

Tropical Swamp

Growing season, temperature, travel and disease

• Growing Season: From all year to 40/60 days.
• Average Temperature: 30 °C (86 °F) to 15 °C (59 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to 0 °C (32 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 4, rarely 6 due to winter.
• Forageability: 75%.
• Grazable: Most of the time, during growing season.
• Disease frequency: 2.0 per year.

Flora

Alocasia, Berry bush, Bush, Chokevine, Clivia, Cypress tree, Giant rafflesia, Low shrubs, Maple tree, Tall grass, Willow tree, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Alpaca, Boomalope, Capybara, Cassowary, Chinchilla, Cobra, Elephant, Guinea pig, Monkey, Panther, Rat, Rhinoceros, Tortoise, Wild boar

Hot biomes

These biomes become progressively dry as they become more arid. Moderate amount of flora and fauna, which drops off as you pick a more extreme biome. Mostly year-round growing periods. Traveling in those biomes is usually fast and rarely slowed by cold seasons.

Arid shrubland

A dry region, but not dry enough to become a true desert. Open plains with grasses and bushes give way to scattered groves of trees. Plants are hardy and there is a moderate density of animals, but arable soil is hard to find.

Arid Shrubland

Growing season, temperature, travel and disease

• Growing Season: From all year to 40/60 days.
• Average Temperature: 30 °C (86 °F) to 15 °C (59 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to 0 °C (32 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, rarely 3 due to winter.
• Forageability: 50%.
• Grazable: Most of the time, during growing season.
• Disease frequency: 0.9 per year.

Flora

Agave, Berry bush, Bush, Dandelions, Drago tree, Grass, Pincushion cactus, Saguaro cactus, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Bison, Boomalope, Boomrat, Cougar, Donkey, Dromedary, Elephant, Emu, Fennec fox, Gazelle, Guinea pig, Hare, Horse, Iguana, Megasloth, Ostrich, Rat, Rhinoceros

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Desert

A very dry area which supports little life. There is very little arable land, and animal life is very sparse. Deserts can be hot, or quite cold.

With so few animals to hunt, growing crops is a priority on one of the few arable patches. The hot temperatures can cause problems for colonists and tamed animals. This biome has patches of soft sand which prevent building, but can be removed with moisture pumps.

Desert

Growing season, temperature, travel and disease

• Growing Season: From all year to 10/60 days.
• Average Temperature: 30 °C (86 °F) to 0 °C (32 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to -25 °C (-13 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, but sometimes 3 due to winter.
• Forageability: 25%.
• Grazable: Only during growing season.
• Disease frequency: 0.7 per year.

Flora

Agave, Bush, Dandelions, Drago tree, Grass, Pincushion cactus, Saguaro cactus, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Boomalope, Cougar, Donkey, Dromedary, Emu, Fennec fox, Gazelle, Guinea pig, Iguana, Ostrich

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Extreme desert

An extremely hot, dry area, devoid of almost all life. Searing heat and a near total lack of arable land make it very difficult to survive here.

The hot temperatures can cause problems for colonists and tamed animals. Its warm enough for growing plants outdoors, but it has to be done in stony patches around hills and mountains. Even though potatoes grows better in stony soil, you need to plant rice first so you will not starve while waiting for potatoes. Strawberries are also a good idea since there is no wood for cooking. Later hydroponics can be used instead of ground. This biome has patches of soft sand which prevent building, but can be removed with moisture pumps. Animal migrations may occur, about once every other year.

Extreme Desert

Growing season, temperature, travel and disease

• Growing Season: From all year to 30/60 days.
• Average Temperature: 30 °C (86 °F) to 10 °C (50 °F).
• Temperature Variation: From 35 °C (95 °F) in summer to -5 °C (23 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, rarely 3 due to winter.
• Forageability: 0%.
• Grazable: Never.
• Disease frequency: 0.7 per year.

Flora

Agave, Grass, Saguaro cactus, Gauranlen tree , Timbershroom 

Fauna

Donkey, Dromedary, Fennec fox, Guinea pig, Iguana

Cold biomes

These biomes become progressively colder and hostile as they become more intense. Flora and fauna becomes more scarce as you pick a more extreme biome. Mostly seasonal growing periods but may go down to no growing period in more extreme biomes. Traveling in those biomes is usually slow due to marsh and cold seasons which can be very long.

Boreal forest

Forests of coniferous trees. Despite the harsh winters, boreal forests sustain a diverse population of small and large animals, and have warm summers.

Boreal Forest

Growing season, temperature, travel and disease

• Growing Season: 30/60 days to 10/60 days.
• Average Temperature: 10 °C (50 °F) to -10 °C (14 °F).
• Temperature Variation: From 25 °C (77 °F) in summer to -35 °C (-31 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, but often 3 due to winter.
• Forageability: 75%.
• Grazable: Only during growing season.
• Disease frequency: 1.0 per year.

Flora

Berry bush, Birch tree, Brambles, Bush, Grass, Moss, Pine tree, Poplar tree, Wild healroot, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Arctic fox, Arctic wolf, Caribou, Cougar, Deer, Elk, Grizzly bear, Hare, Horse, Ibex, Lynx, Megasloth, Muffalo, Raccoon, Rat, Red fox, Squirrel, Timber wolf, Turkey, Warg, Wild boar, Yak

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Cold bog

A wetland packed with trees and vines. Much of the marshy land here can't support heavy structures, moving around is slow due to choking vegetation. Disease is endemic in this dense, wet ecosystem.

A more wet version of the Boreal Forest. Like in all swamps, diseases are more common. The marshy soil will probably require bridges before constructing buildings and the terrain is really slow to travel, but this biome also has more fertile soil.

Cold Bog

Growing season, temperature, travel and disease

• Growing Season: 30/60 days to 10/60 days.
• Average Temperature: 10 °C (50 °F) to -10 °C (14 °F).
• Temperature Variation: From 25 °C (77 °F) in summer to -35 °C (-31 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 4, but often 6 due to winter.
• Forageability: 50%.
• Grazable: Only during growing season.
• Disease frequency: 1.3 per year.

Flora

Astragalus, Berry bush, Bush, Chokevine, Cypress tree, Maple tree, Moss, Tall grass, Wild healroot, Willow tree, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Arctic fox, Arctic wolf, Caribou, Cougar, Deer, Elk, Grizzly bear, Guinea pig, Hare, Ibex, Lynx, Megasloth, Muffalo, Polar bear, Raccoon, Rat, Red fox, Squirrel, Timber wolf, Turkey, Warg, Wild boar, Yak

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Tundra

These mostly-frozen plains bear almost no trees and little vegetation. There are a few small animals interspersed with large herds of migratory grazers and their predators. Animal migrations may occur once or twice per year.

Growing periods are generally very short or non-existent.

Tundra

Growing season, temperature, travel and disease

• Growing Season: 20/60 days to never.
• Average Temperature: 0 °C (32 °F) to -20 °C (-4 °F).
• Temperature Variation: From 25 °C (77 °F) in summer to -50 °C (-58 °F) in winter.
• Roads and Rivers: Yes.
• Movement Difficulty: 1, but most of the time 3 due to winter.
• Forageability: 50%.
• Grazable: Only during growing season.
• Disease frequency: 0.8 per year.

Flora

Astragalus, Berry bush, Birch tree, Bush, Dandelions, Grass, Moss, Pine tree, Wild healroot, Harbinger tree , Gauranlen tree , Timbershroom , Anima tree 

Fauna

Arctic fox, Arctic wolf, Caribou, Elk, Grizzly bear, Hare, Ibex, Lynx, Megasloth, Muffalo, Polar bear, Snowhare, Timber wolf, Warg

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Ice sheet

Sheets of ice which can be kilometers thick. There is no soil for plants to grow in. The only animals here are migrating to somewhere else - or badly lost.

The only land possible to farm is stony patches around hills and mountains, but they need to be heated indoors and also have sun lamps. You will need to hunt, trade and cannibalize until you get a heater and a sun lamp. Later, moisture pumps can create larger growable areas and hydroponics can be used instead of ground. Geothermal vents can be used for free heating. With so few animals here, any predators that roam in will become hungry soon and target your colonists and animals.

Ice sheet never have ruins.

Ice Sheet

Growing season, temperature, travel and disease

• Growing Season: Never.
• Average Temperature: -20 °C (-4 °F) to -40 °C (-40 °F).
• Temperature Variation: From 10 °C (50 °F) in summer to -70 °C (-94 °F) in winter.
• Roads and Rivers: No.
• Movement Difficulty: 1.5, but most of the time 3.5 due to winter.
• Forageability: 0%.
• Grazable: Never.
• Disease frequency: 0.7 per year.

Flora

None.

Fauna

Arctic fox, Arctic wolf, Lynx, Megasloth, Muffalo, Polar bear, Snowhare

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Sea ice

Permanent ice sheets floating on water. There is no soil for plants to grow, no minerals to mine, and almost no animal life.

Sea Ice does not have ruins and geothermal vents. Deep drills cannot dig up stone chunks and moisture pumps will only generate more ice, which means it is impossible to grow anything on the ground. You will need to do hunting, trading and cannibalism until you get a heater, a sun lamp and a hydroponics basin. It is worth mentioning that Sea Ice was designed to not allow colony building, only to allow traveling in the area, even though it is possible.

Sea Ice

Growing season, temperature, travel and disease

• Growing Season: Never.
• Average Temperature: -20 °C (-4 °F) to -30 °C (-22 °F).
• Temperature Variation: From 10 °C (50 °F) in summer to -60 °C (-76 °F) in winter.
• Roads and Rivers: No.
• Movement Difficulty: 1.5, but most of the time 3.5 due to winter.
• Forageability: 0%.
• Grazable: Never.
• Disease frequency: 0.7 per year.

Flora

None.

Fauna

Arctic fox, Arctic wolf, Muffalo, Polar bear, Snowhare

Version history

• 0.6.532 - Added
• 0.7.581 - Tropical rainforest added.
• 0.8.657 - Boreal forest and tundra added
• 0.11.877 - Ice sheet now playable.
• 0.13.1135 - Extreme Desert biome added.

When generating the world, the land masses form first, followed by rivers. An ancient society is then shallowly simulated to generate ancient roads, and modern settlements and roads are generated (often alongside ancient roads).

Create world

The world generation screen appears during the creation of a new colony.

SEED A random seed is provided, but you may enter your own. A given seed always produces the same map layout:

• ludeon: USA

RANDOMIZE SEED Randomly picks a new seed.

GLOBE COVERAGE What percentage of the overall globe is generated. Larger globe coverage generates a fuller world, but takes a longer time to load up, and can also impact performance on lower-end systems.

Optional maps sizes:

• 5% (Dev Mode)
• 30%
• 50%
• 100%

GENERATE Click to continue with the current settings.

Advanced

Allows choosing between map sizes and starting season:

Small

• 200 x 200 (40,000 cells)
• 225 x 225 (50,625 cells)

Medium

• 250 x 250 (62,500 cells)
• 275 x 275 (75,625 cells)

Large

• 300 x 300 (90,000 cells)
• 325 x 325 (105,625 cells)

Ludeonicrous

• 350 x 350 (122,500 cells)
• 400 x 400 (160,000 cells)

Landing site

The world will generate made up mostly of hexagons and a few pentagons, then the 'Select landing site' screen appears. Clicking a tile will show its information with its own average temperature, biome, elevation, terrain and rainfall amount. Clicking the Mode button (default is 'Full') offers the choice to view the map in a special heat map. Tiles are coherent to their neighboring tiles, by following alike patterns. Each biome has its own flora, fauna and growing periods.

Moreover, its possible to choose between mainland and islands. There is no way to navigate across the seas and oceans, which will require the alternative method of researching Transport pod to overcome the vast body of water.

Biomes

Main article: Biomes

There are nine biomes in Rimworld and—on a normally generated world—all of them are represented. They each correspond to specific features. Each biome is more likely to include certain features based on it's real world equivalent.

Features

There are several main features that affect game play in that tile on a generated world. These details are listed on-screen for the selected map tile.

Elevation

A map tile's distance above sea level is its elevation. Higher elevation brings with it colder weather.

Latitude

The coordinates of a map tile includes its latitude which affects its temperature range and amount of daylight. In polar latitudes the sun may not set or rise completely for a long time.

Rainfall

Each map tile has a certain amount of rainfall, given in average number of millimeters per year. It determines how often it will rain, not counting the automatic rain after a certain number of fire tiles are on the map.

Terrain

Each map tile has one of the following terrain types: Flat, Small Hills, Large Hills, and Mountains. The terrain type determines the amount of mountain will be generated on the in-game map.

Temperature

Main article: Temperature

Each tile has its own averages for temperature based on the biome. Only the averages are presented in the world generation menu, but can directly affect your game. The effects of temperature vary greatly; extreme heat causes your colonists to develop heat stroke, while extreme cold may freeze them so thoroughly, their corpses will never decay. Temperature is related to the other three features of a tile in a generated world. Naturally, higher elevation and a more northern biome is colder.

Quadrums

Each year in a Rimworld planet is separated into 4 quadrums: Aprimay, Jugust, Septober and Decembary.

The quadrums are the same across the planet, however the corresponding seasons are reversed between the northern hemisphere and the soutnern hemisphere.

Roads

In Alpha 17, there are now roads winding across the world. They double the speed of any caravans using them, and factions tend to settle near roads. Visitors, caravans, traders or raiders are also tend to arrive and leave on a road.

They come in 5 types: path, dirt road, stone road, ancient asphalt road and ancient asphalt highway. They are functionally the same, with difference only being appearance when generated on a map.

Dirt roads use packed dirt, stone roads use flagstones of the local stone and ancient asphalt roads use broken asphalt. None of these can be disassembled for resources.

Sometimes other objects will generate alongside roads, for example the ancient concrete barrier or ancient lamppost alongside the ancient asphalt highway. These serve no function except cover or disassembly for steel.

Rivers

Also in Alpha 17, there are rivers that flow towards the oceans and can merge with each other. They are more likely to generate in rainy areas.

When a map is generated in a tile with a river, there will be a belt of flowing river dividing the map. The river cannot be built over or pumped dry using the moisture pump, thus effectively splitting your future bases apart.

They come in 4 sizes, huge river, large river, river, and creek. It affects the width of the river, and also the proportion of shallow moving water, which can be walked over, to deep moving water, which can't be walked over.

Factions

Pressing the 'Factions' button allows you to view the different factions in the world.

There are three kinds of faction: outlanders, tribes and pirates. There are a total of five, and a maximum of three each. You can see the relation between them and you.

Their bases tend to be located near roads, and you cannot settle right next to one.

Factions are not tied to the world seed. Pressing "back" and "Generate" again will alter the list of factions and the locations of their bases.

Misc

There are a total of 12 pentagons in the world, with the coordinates as such:

• 31.72 S, 0.00 W
• 31.72 N, 0.00 W
• 31.72 N, 180.00 W
• 31.72 S, 180.00 W
• 0.00 S, 58.28 E
• 0.00 S, 58.28 W
• 0.00 S, 121.72 E
• 0.00 S, 121.72 W
• 58.28 N, 90.00 E
• 58.28 N, 90.00 W
• 58.28 S, 90.00 E
• 58.28 S, 90.00 W

Besides being differently shaped to allow gap-free tiling of the whole world, they function no differently from regular world tiles.

Navigation & Site selection

The player can click 'Select random site' or select one of the squares in which to land and build a colony.

Keyboard/mouse controls:

Mouse Controls
Left mouse button	Select location
Right mouse button	Clear selection
Mouse wheel	Zoom in/out
Mouse wheel (click+hold)	Pan

Keyboard Controls
PageUp	Zoom out
PageDown	Zoom in
Arrow up or W	Pan up
Arrow down or S	Pan down
Arrow left or A	Pan Left
Arrow right or D	Pan Right