This article is for the PC version of Stellaris only.
Typical colonization method
Each species begins with a partially-developed Homeworld. This world is always of the type chosen during Empire creation, and always has 16 or more surface tiles and a hardcoded habitability of 100% for that species. Some of the tiles are blocked by Sprawling Slums and Industrial Wastelands, special Tileblockers that need fewer resources and no technology to remove. In order to expand, the species can build colony ships to send to other habitable worlds after building outposts in the star systems.
Throughout the entire game, any planet within your borders can be colonized. The primary source of habitability is from the species Habitability trait: Planets of the same type have 80% Habitability, planets within the same Hydrosphere group have 60%, and planets belonging to other groups have 20%. Gaia Worlds, habitats, city worlds, and Ringworlds always have 100% Habitability for any species. On the flip-side, Tomb Worlds start at 0% habitability for most organic species. However, there is a Rare Society tech which gives +20% habitability to Tomb Worlds.
Habitability affects organic life in the following ways:
- For all organic life, low Habitability increases the resource upkeep of all pops on the planet.
- The increase is whatever percentage the planet is from ideal, an 80% world would give the pops 20% extra upkeep, whereas a 0% world such as a tomb world doubles resource upkeep. This means that colonizing a planet with poor habitability is not nearly as punishing as before although it is still a good idea to stick to the highest Habitability possible until you economy is strong enough to sustain the increased upkeep.
Typically, in order to colonize other planet types, you must do one of these things:
- Terraform the planet to a more habitable type.
- Increase the diversity of your empire to include a species that can colonize other planet types. If you conquered primitives, you need to wait for culture shock to wear off.
- Complete the research items that increase the species' habitability empire-wide. (i.e. Hostile Environment Adaption, Foreign Soil Enrichment, etc.).
- Use Droid or Synthetic pops as initial colonists.
Habitability is the measure of how well a species can live on a planet. Every species has a climate preference for one of the primary habitable world types. A planet's habitability (and terraforming cost) is determined by its climate. The 9 habitable worlds are divided into 3 climate categories: dry, frozen and wet. Megastructures, Gaia and Ecumenopolis worlds have maximum habitability for all species while Tomb Worlds and Machine Worlds are normally uninhabitable by biological species.
|Gaia, Ecumenopolis and Ring World||100%|
|Exact Match or Habitat||80%|
|Tomb World and Machine World||0%|
- Every 1% of Habitability under 100% increases the Pop Upkeep and Amenity Usage by 1%, reduce their job output and Pop Growth by 0.5% and happiness by 0.25%. It caps at 0% Habitability, giving +100% Pop Upkeep and Amenity Usage, -50% Job Output and Pop Growth and -25% happiness.
- Homeworlds have a +30% habitability for the species originating on them.
- Low Habitability can also trigger events.
Systems containing surveyed or non-surveyed habitable worlds will have one or more planet icons that are either green, yellow, orange, red, or blue, depending on the habitability percentage and/or status of the planet(s) in question.
- Green: The world is ≥70% habitable for at least one species in the player's empire.
- Yellow: The world is 40–69% habitable for at least one species in the player's empire.
- Red: The world is <40% habitable for all species in the player's empire.
- Orange: The world is habitable but not surveyed.
- Blue: The world is currently being Terraformed.
Sometimes other factors can prevent colonization of a world. Some common reasons for not being able to colonize an otherwise habitable world are:
- There is an anomaly on the world which has not yet been researched
- The world is inhabited by a pre-FTL civilization
Zooming in to the system and hovering over the planet icon may reveal useful information about what is preventing the player's empire from colonizing the world. e.g. If the tool tip says the world is 'controlled by Unidentified Empire' or 'belongs to someone else', another empire is in control of the system. In this case, surveying the world will reveal the empire that controls it. This action can cause the player's science ship to be missing in action for up to a year, so it may be preferable to avoid surveying the world.
Since different species can have different world type preferences, it can be better for an empire to populate its worlds with other alien species, genetically-engineered subspecies, or even robots/synthetics.
It is also possible to terraform habitable worlds, though this is a costly and time consuming process. Only planets of the main types (continental and such) can be terraformed, in addition to tomb and barren worlds with the "Terraforming Candidate" modifier.
Using genetic modification, one can create a subspecies of the empire's primary species that is suitable for the Climate in question. However, this needs either the first-in approach (so they can be changed on the new Planet) or a staging area with increased Habitability regardless of current Climate Preference (Ringworld, Habitat, Homeworld, rare modifiers).
With all the possible habitability types, there are bound to be some aliens that can live comfortably on planets which are unsuitable to the primary species. The main disadvantage is that xeno pops have increased Unity cost per pop and might not have favorable traits. There may also be unwanted Xenophile attraction/Faction interactions from this path.
Both via Conquest and Migration Treaties, one can add xeno pops to the Empire to use as colonists. If the empire is Xenophobe, the rights limitations for xenos will make the pops also considerably less happy. The migration approach requires a "first-in" colonist.
Genetic Uplifting, Enlightenment and Infiltration can be used to acquire a xeno species as well. With the first one, it might even be possible to get a rare Habitability like Tomb Worlds. Very rare species native to Tomb Worlds are extremely adaptive and can thrive on any kind of planet (every normal class is secondary). The usual way of obtaining these species as subjects is finding them as upliftable semi-sentients on Tomb Worlds and uplifting. The event chain Horizon Signal can also create a subspecies of your main species with this trait. Alternatively, pops of your main species on Tomb Worlds may mutate and develop into their own species native to Tomb Worlds.
All robots, including the primary species of Machine Intelligence empires, have 100% Habitability on every kind of inhabitable world. However, only drones and synthetics can actually be colonists. Synthetics are good to superior in all tasks, but also increase the Unity costs. Robot pops furthermore have a massive draw towards Materialist ethics, both for themselves and other pops on the planet. Droids or synths make particularly good "first in" colonists, if they can be moved off or Materialist attraction is acceptable.
Choosing systems to build outposts
Planets differ mainly by habitability and size and which of these two should be your primary focus depends on the Empire you are planing on playing. Habitability is important if you are going for a high happiness build (as lower habitability gives a happiness penalty) or if you want rapid population growth. Size is important because it determines the maximum number of districts a colony can support. Having a large number of planets (regardless of habitability and sizes) can be useful for gathering minerals and energy credits to fuel fleets.
Other things worth considering:
- Planetary features - Planets have random features that determine the number of Districts it can support. You should focus on colonizing planets that can support a large number of Districts most needed by your empire in the short term, or long term. Certain planets can also have rare features that are a great boon.
- Planetary modifiers - There are over 20 planetary modifiers for some planets, visible as big circles on top of planetary surface screen. They impact yields (for example "Mineral rich" increases extracted mineral yields by 25%) or population in positive or negative way. Some of them are fairly minor, but others have a huge impact.
- Blockers - Almost all uninhabited planets have some Blockers. Blockers are "natural obstacles" randomly generated on tiles and preventing them from being colonized, developed and exploited. They vary from toxic swamps to volcanoes, and each Blocker type has a corresponding technology which can be used to clear it - for a cost in minerals and energy. In the early game, when you have neither proper technology nor resources enabling you to remove Blockers, you should avoid colonizing planets very densely covered in them, as you won't be able to properly develop them for a long time. However, by mid to late game, Blockers become more and more insignificant obstacles and you shouldn't worry about them.
- Political location of a planet - If you build outposts in systems too close to alien empires, they may be very distressed of you suddenly expanding your imperial borders close to them, and declare you a rival or even declare a war. There is a negative "Border friction" modifier in diplomacy when two empires aggressively expand near each other. You should be very careful about colonizing planets near to Fallen Empires borders, especially if they are Xenophobic - and keep an eye out for Gaia Worlds marked by the Holy Guardians, as well. That said, sometimes proximity is a benefit rather than a drawback: one can easily "hem in" an empire to cut off their expansion.
Later in the game, choosing what planet to colonize isn't that big of a challenge as you will presumably have enough spare resources and technology to cope with any natural obstacles and shortages. However, early game prioritization of good planets is very important. Consider these three potential colony planets:
- A large planet with 3/4 of its features covered by Blockers.
- A planet possesses an irradiated modifier which makes pops grow very slowly and unhappily.
- A modestly sized planet that also has decent resources and tiles mostly free from obstacles.
Under these circumstances, you should consider colonizing number 3. However, the right choice isn't always that obvious.
To colonize a planet, you need to send a colony ship after building an outpost in the system. They can be built at an empire's homeworld from the start of the game; once a colony has been established (past the -8 energy credits/mth phase), it can also create colony ships.
Colony ships cost a base of 300 minerals, modified by happiness modifiers, and take a year to build. While ordering its construction, you have to choose what pops of a planet constructing it will become colonists. This pop will not be "removed" from the surface of an origin planet. On board the colony ship, you can put pops of your main species, other species inhabiting your empire, or advanced robots (precisely, Droids or Synthetics - early Robots cannot colonize planets as they are not sentient at all).
Once the Colony Ship is constructed, it costs 8 energy credits to maintain each month - thus you should quickly send it to colonize some planet and not waste your income.
When you click on the existing Colony ships, go to the Galaxy View. You may notice colorful globe icons displaying above systems. A green globe means there is a colonizable planet of high habitability in that system, yellow means there is a colonizable planet but it has medium habitability, red means low habitability planets, usually under the Colonization threshold.
To colonize a planet, select the colonization ship, right click on the planet you want to settle, and choose Colonize Planet. You will be prompted to choose where your colony ship will make planetfall.
Colonization in progress
When a Colony Ship lands on a planet it will be converted into a Reassembled Ship Shelter, which acts as the new planet's capital building and can be upgraded as the population grows. After the landing period of initial development will then occur. This is initially one year, but can be reduced empire-wide by researching the appropriate technologies:
- AI-Controlled Colony Ships
- Self-Aware Colony Ships
- Frontier Collectives
- Frontier Commissars
While the colony is being established, it is extremely vulnerable: just a few days of orbital bombardment will wipe it out completely.
During this period the new colony does not produce anything and consumes Energy. Once the colony has been successfully established, a Pop will appear and take a Colonist Job while another Pop will be growing and will take the second Job. You can then begin to develop the planet by constructing Buildings, clearing Blockers, and moving Pops.
Growing the colony
Your new planet will take time to settle. While the colony is establishing itself it will be a steady drain on your economy (-8, the same monthly energy cost as the colony ship). Once the colony is established, this economic anchor will end and the planet will be a part of your core system (unless the colony was founded in a system belonging to a Sector - then it will go under sector's autonomic governance).
Colonized worlds will have your Core Sector governor governing them. Depending on their bonuses, the governor will give different benefits to the planets they have been assigned to manage. Systems containing colonized worlds can also be assigned to Sectors, which will manage most aspects of their development and contribute all generated Research, plus a set percentage of Minerals and Energy Credits generated, back to your empire.
In the beginning, a colony has only one pop working in one building, the Reassembled Ship Shelter. It is a temporary shelter and you can't build most buildings, only districts, unless you have a proper Administration building. However, Administration requires the planet to have 10 population units.
There are few ways to quickly increase the population of a new colony to 10:
- Maintain an empire-wide food surplus
- Force resettlement, if your policies allow
- Build robots - they count towards required 5 population units, and grow independently from organic pops, effectively doubling growth
Once you finally hit 10 population units, you may upgrade the ship shelter to an Administration Center, at that point the planet is finally "civilized" and can have a Specialization.