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.

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.

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.

Optional maps sizes:

  • 5% (Dev Mode)
  • 30%
  • 50%
  • 100%

Generate Click to continue with the current settings.

Once the player clicks Generate, the 'Select landing site' screen appears and shows the world map, made up of mostly hexagons with a few pentagons thrown into the mix. Every tile on a world is unique, with its own biome, elevation, average temperature, terrain, and rainfall amount. These details are shown whenever the player selects a tile. In world generation four main features, biome, elevation, temperature, and rainfall, are generated with each tile. Clicking the Mode button (default is 'Full') offers the choice to select a feature to view the map in a special heat map. Each feature is logical with the tiles near to them. Each feature goes along with the biome of the tiles and the tiles around it. Each biome has its unique trees, animals, temperatures, rainfall and growing periods.

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


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.


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 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.


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 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 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.

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