World generation

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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.

There are 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. The seasonal differences are also less pronounced near the equator, with there being a permanent summer in it.

When reloading the world after opening the colony, the game shows a loading screen.

Generation process

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:

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.

Configurable map sizes:

• 5% (Dev Mode)
• 30%
• 50%
• 100%

GENERATE Click to continue with the current settings.

Landing site

Upon clicking Generate on the previous screen a new world is generated. The world will be made up mostly of hexagons and a few pentagons. Here the player can choose a tile to land on, or use the 'Select random site' button. Clicking a tile will show its information including its biome, terrain, overall weather, and growing period. For controls, see Controls

It's possible to choose an island to land on, however caravans cannot cross water tiles. Reaching the mainland would require the use of transport pods.

Advanced settings

The 'Advanced' button accesses these options:

• Starting season: Recommended to leave as Auto or Spring for new players.
• Map sizes: Sets the size of the local map where main gameplay takes place.
  • 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)

Factions

The 'Factions' button displays the different factions in the world.

There are three kinds of factions: outlanders, tribes and pirates. There are a total of five, and a maximum of three each. The colors on the factions screen help identify them on the world map. Also shown is each faction's relation with your colony and with each other.

You can never land or settle directly adjacent to a faction base.

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.

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.

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 four 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, and it is permanent summer near the equator.

Roads

There are 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

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 pumped dry using the moisture pump. In version 1.0, rivers can now be built over using bridges. There is also a watermill generator, added in Beta 19, which requires research before it can be built. Watermill generators must be built adjacent to moving water.

Rivers 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.

Caves

In Beta 18, you may find caves in mountains. In those caves you may find insect with a dormant hive (mean that they won't spawn any additionnal hives or insects) and harvestable mushrooms.

Dormant hives

Hives can be a valuable source of food if you steal their jelly while the defenders are asleep. If an insect is asleep on a stack of jelly or other item, do not try to take it or you may awake them and put your colonist in peril. Colonists' default threat response may activate upon seeing insects, even if the insects are asleep. So be careful that your jelly harvesters are not set to "Attack" by default.

The hive and its insects can be harmed without any colonist actions. Insects may suffer from extreme temperatures; cold snaps will kill the weaker ones. Insects will be aggressive towards humans, but mutually non-hostile with wildlife. A wild man or woman counts as wildlife.

However, hungry predators may try to hunt them. Most of the time the predator will be killed, but may down some insects by wounding them. When the insects die, you can unforbid and collect the corpses for butchering, by the same method used to harvest insect jelly.

Cave flora

You may find Agarilux, Bryolux or Glowstool in these caves. Instead of needing light to grow, they die when exposed to excess sunlight.

Settlements

On the World map, Outlander settlements will have a house icon, Tribal settlements will have a tent and Pirates will be a skull and crossbones. Your colony's settlements will be teal (light blue), with the appropriate icon for the starting scenario you chose.

Other factions appear as follows:

• Outlanders (blue for rough, purple for civil)
• Tribals (green for savage, yellow for gentle)
• Pirates (red skull and crossbones)

Faction settlements tend to be located near roads, and you cannot settle right next to one. If you choose a location within 4 tiles of another faction's settlement, the game warns you that this will decrease your relations.

Since Beta 18, factions are tied to the world seed so factions and their settlements are always generated in the same place.

Landforms

Each major feature has a name generated with it. This includes biomes, lakes or oceans, mountain ranges, etc.

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.

Controls

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