World generation

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Game Creation Scenario system AI Storytellers World Generation Biomes

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 Alpha 16 (December 20th, 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.

During the world generation process, a world is created using a seed. A seed is a number or string used to initialize an algorithm. Each world is randomly generated using this algorithm and will consist of several different biomes. The world will generate an amount of the different biomes listed below with different terrain properties, including things such as height of terrain and rainfall. Once the world map is generated and displayed, the player can choose which of 8 playable biomes (9 in Alpha 16) they want to land in; each offering their own sets of flora and fauna, chance for diseases, and their own unique sets of challenges.

The game splits the biomes into 3 categories: Moderate, Arid, and Cold. Here are the categories and biomes listed below, in order of intensity:

A16 World Map

The following diagram is a simple chart of biomes by intensity, and therefore you could view this to see which biome could best suit your experience or playstyle: Biome Intensity Diagram

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.

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.


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.


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


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


The coordinates of a map tile includes its latitude which affects its temperature range and amount of daylight (unconfirmed).


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.


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.


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.


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