This article is for the PC version of Stellaris only.
An Empire is a group of planets and star systems that are ruled by the same government and controlled by a single player (or AI). Empires may have a variety of governments such as a democracy, oligarchism, despotism or imperial rule.
Ethics are the most defining features of a space empire; they affect the behavior of AI empires, likely technologies, available policies and edicts, valid government types, the opinions of other empires, and - perhaps most importantly - provide the fuel for internal strife in large and diverse empires. Civics are the second-most defining features of a space empire; they affect the finer details of the empire's internal structure as well as having certain effects on the empire's behavior.
It should be noted that the name of the player empire and its government structure can always be changed in the government window.
Each empire starts with a homeworld that is generated according to a different set of rules than randomly spawned habitable planets. A homeworld can spawn either as an independent planet (and can even have rings or natural satellites orbiting it) or as the moon of a gas giant. Below is a summary of the different homeworlds and their features. Note that the table shows the number of districts available right at start. Clearing blockers will add to those numbers. Each species has double weight for pop growth on its homeworld.
|Organic||16-20||6||6||7||1 pop blocker (depends on authority)
Two random +2 districts (depends on authority)
|Planetary Features are determined by climate but the total number of districts available is always the same.|
|Lithoid||16-20||6||9||4||1 pop blocker (depends on authority)
Two random +2 districts (depends on authority)
Lithoid Monoliths (x4)
|Primary species is Lithoid||Does not replace Earth's Planetary Features or blockers.|
|Machine||16-20||8||6||3||1 pop blocker (depends on civics)
Abandoned Strip Mine
|Machine Intelligence||Does not replace Earth's Planetary Features or blockers.|
|Gaia||25||8||7||8|| Sprawling Slums
Industrial Wasteland (x2)
|Life-Seeded civic||Increases Earth's size but does not replace its Planetary Features, resulting in a smaller number of specialized District slots.|
Adds +1 Bubbling Swamp, Crystalline Caverns and Dust Caverns Planetary Features even if the homeworld is Earth.
|Tomb||16-20||6||6||6|| Settled Ruins
|Post-Apocalyptic civic||Does not replace Earth's Planetary Features or blockers.|
|Tomb||16-20||7||6||3|| Former Organic City
|Determined Exterminator civic||Clearing the Blockers unlocks unique Planetary Features.|
|Earth||16||6||7||5|| Sprawling Slums
Great Pacific Garbage Patch
|Sol starting system||Earth has its own unique set of Planetary Features and Blockers that will always be the same, regardless of circumstances.|
The United Nations of Earth and Earth Custodianship preset empires start on Earth by default but cannot appear at the same time.
|Unity||18||6||6||7||1 pop blocker (depends on authority)
Two random +2 districts (depends on authority)
|Deneb starting system||It is identical to regular organic starting planets in every way except that its size is fixed at 18.|
The Commonwealth of Man preset empire starts on Deneb by default.
Will always be a moon orbiting a gas giant.
The capital is the ruling seat of an empire and is oftentimes its most important world. An empire's capital can be moved once every 10 years for a cost of 250 influence. The capital is its own world Designation and gets +5 Stability and +10 Amenities and either +100% Governing Ethics Attraction by default or -20 Deviancy if Gestalt Consciousness. An empire's capital planet and system are marked by gold star corners on the system and galaxy maps.
Empire Sprawl is a measure of an empire's expansion, both tall and wide, relative to its administrative capacity and increases the cost of Technologies, Traditions, Leaders and Edicts if the sprawl exceeds the administrative capacity. Empire Sprawl is increased by 2 for each system, planet and owned Branch Office, and by 1 for each district.
Administrative Capacity represents the bureaucratic assets available to administrate the empire. If the Empire Sprawl exceeds the Administrative capacity, then every point of Empire Sprawl exceeding the Administrative Capacity will impart the following penalties:
- +0.3% Tech cost
- +0.5% Tradition adoption cost
- +1% Campaign (Subset of Edicts) cost
- +1% Leader Upkeep cost
- +1% Leader Cost
An empire's base Administrative Capacity is 30, increased by the following:
- +10 Pacifist ethic
- +20 Fanatic Pacifist ethic
- +20 Efficient Bureaucracy civic
- +20 Colonial Bureaucracy research
- +20 Galactic Bureaucracy research
- +15 Administrative Efficiency repeatable technology
- +20 Courier Network / Limited Autonomy / Extensible Software Tradition
- +30 Imperial Prerogative ascension perk
- +20 Divided Attention civic
- +20 Corporate authority
- +10 Private Prospectors civic
- +20 Oracle empire modifier
Assuming that each point added to your empire is equally productive the effect of empire sprawl is to make the rate of your technology, campaign, and tradition production tend to a limit - equivalent to 100 points of admin for campaign edicts, 200 for traditions and 333 for technology. This means that normally going over the administrative capacity of an empire leads to diminishing returns. Your admin capacity being over the cap can lead to minor reductions in productivity, however, should largely be considered inconsequential compared to the benefits for going over the cap. Leader costs are significantly more complex as the number of leaders an empire requires increases as the empire becomes larger.
Empire Cohesion, as the name implies, is a measure of the overall cohesiveness of an empire's territory. If the cohesion loss is greater than the total cohesion gain, an empire's Sprawl will be multiplied and thus put greater administrative strain upon it. Cohesion is raised or lowered by the following:
- +1 for each owned system
- +3 for each upgraded Starbase
- -1 for each hyperlane connection outside the empire's borders
- -3 for each unowned system that only connects to your empire
Empire Cohesion is especially important in games set with a high hyperlane density. Full hyperlane density in particular limits the use of outposts due to every system having on average 6 connections. The maximum value for cohesion is 100%.
Sectors are administrative regions within an empire. Every empire will start with a core sector, named after the homeworld and extending up to four hyperlanes away from the capital. Any planet colonized more than four hyperlanes away can be selected to become the sector capital of a new sector, with the planet becoming marked by blue star corners on the system and galaxy maps. The new sector will extend up to four hyperlanes away from the sector capital. Wormholes and Gateways are not counted for this calculation. Each sector can have a Governor assigned to it.
All sectors, including the core sector, can be given a Sector Focus. Choosing a Sector Focus will make the sector develop itself automatically towards a given direction as long as it has resources, reducing micromanagement. Resources can be added to a Shared Stockpile for all Sectors to use or given manually to each Sector. Shared and Sector stockpiles are limited to the amount of energy credits you may store. Beyond that, it is wasted.
Relative Power is a measure of how much empires are ahead of one another in terms of resource production, fleet power or researched technologies. A Relative Power of Superior//Inferior means that an empire has 50% more (1.5x) resource production, fleet power or researched technologies and a Relative Power of Overwhelming/Pathetic means that an empire has 150% more (2.5x) resource production, fleet power or researched technologies.
Relative Power is split into three categories: Fleet Power, Economic Power and Technology Level.
Fleet Power: The combined fleet power of every owned fleet.
- +1 per 1 Fleet Power
Economic Power: A weighted sum of all monthly income, including income from trade agreements. Monthly spending is not part of this score. The various resources are weighted the same as their base market price (base energy price for 1 unit):
- +1 per basic resources
- +2 per Consumer Goods
- +4 per Alloys
- +10 per advanced resources
- +20 per strategic resources
Technology Level: 200 + the combined base Tech Cost of all researched technologies, divided by 100. Repeatables only count 0.33x as much as regular technologies.
- +200 Base Technology Level
- +0.01 per 1 base Tech Cost of all researched regular technologies
- +0.0033 per 1 base Tech Cost of all researched repeatable technologies
The formula to calculate the overall power of an empire is:
Victory score tallies an empire's total accomplishment. The empire that has the highest score when the Victory Year arrives is declared winner. The Victory Year is configurable and can be disabled altogether. An empire will always declare victory, if it's the only one that can do so. All players may continue the game session normally even after an empire declares victory and the victory is, in practical terms, of little concern.
The Victory Window shows a total score for each empire and its ranking, as well as a breakdown by category. The categories are as follows:
Economic Strength: +1 per 1 Economic Power based on Relative Power (Fallen Empires start with +5,000)
Technology Level: +0.25 per 1 Technology Level based on Relative Power
Number of Systems: +10 per system
Number of Colonies: +50 per colony
Number of Pops: +2 per pop, regardless of type
Subject Empires: +50% of a subject empire's score is given to the overlord
Federation: +10% of each other federation member's score is shared by all federation members
Crisis Ships Killed: +10 per crisis ship destroyed
Relics Collected: Each Relic grants a large amount of score. The score of each Relic is shown on the Relics page.
Empire Modifiers are gained through a variety of actions such as event choices or diplomacy with enclaves. They affect the entire empire and as such bring large benefits or penalties.
Permanent Empire Modifiers are always positive and last the entire game. They can only be gained through events.
Renewable Empire Modifiers are always positive and last as long as an empire can afford their upkeep costs.
The following empires can appear during the game as a result of certain events: