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This article has been verified for the current console version (2.2) of the game.
Mammalian Citadel

A starbase is the primary space station used throughout the game and is used for things such like determining the ownership of a given star system, construction, repair and maintenance of ships, collection and transportation of Trade Value in addition to it acting as a strategic fortress during warfare.


A starbase's most fundamental function lies in asserting ownership over a star system. Doing so requires fully surveying the desired system and then constructing a starbase in it. The build cost is 100 Alloys.png Alloys and an additional Influence.png influence cost on top of that. The influence cost is determined by a fixed cost which is then multiplied by the shortest path of hyperlane jumps (gates and wormholes act as "shortcuts") between the target systems and the empire's closest owned system.

Once built, the starbase will appear orbiting the center point of the system. It cannot be destroyed by any regular means but it can still be dismantled by its owner during peacetime if it is of no more than outpost level (higher-level starbases will need to be downgraded to outpost in order to be dismantled). If a starbase is dismantled, the system reverts back to being neutral and unclaimed and can then claimed by any empire.

Besides the initial influence cost, upgrading the starbase to a higher level above outpost level will cost only alloys. Aside from making the starbase more powerful due to better base stats and the addition of more weapon components, the upgrade also allows the owner to fit the starbase with different buildings and modules to increase its defensive capabilities and improve its contribution to the empire beyond its basic role of system control and defense. One such important module is the Spaceport 1.png Shipyard which enables the construction of military ships in the starbase. Having multiple shipyards on a starbase allows it to effectively act as a "fleet manufactory" by constructing several ships in parallel, simultaneously. Shipyards build order is independent from the main build order of starbase.

Though it is not possible to design a starbase, its components will be auto-fitted with the latest advanced technology as soon as they are made available (at no additional cost to the owner).

Warfare behavior[edit]

Systems with starbases bigger than outposts require a higher influence cost to claim (25 influence). Consequently, those starbases grant a higher war-score if occupied successfully (10 occupation value). An additional benefit of upgraded starbases manifests in them including an FTL inhibitor which, as long as the starbase remains active, prevents enemy ships from leaving the system via any hyperlane other than the one they arrived through. This allows an FTL inhibitor-equipped starbase to turn strategically important systems into efficient choke points, delaying hostile fleets from leaving the system and advancing further by forcing them into an engagement which may last long enough for reinforcements to arrive.

During war, an attacker must disable the enemy's starbase within the system in order to seize control of any planets found within said system. As starbases cannot be destroyed, this is achieved by reducing their Health Hull points down to 0, disabling them. The starbase will then remain incapacitated for a duration of Time 30 days (after the latest attack), during which time any military ships in close proximity to the starbase will be able to gain control over it. If the starbase is left unoccupied and is not attacked, it will enter a self-repair phase and become operational again as soon as it regains Health 5% Hull points. If there are multiple empires fighting on one side of the war, the newly-occupied system will then be assigned to the empire with the strongest claim, even if the system wasn't conquered by them.

Occupied starbases are fully operational and can repair ships of the side that controls it, inhibit FTL for "enemy" ships, and manage defense platforms, all empire-wide bonuses will also be applied, including home territory modifiers (The Eternal Vigilance ascension perk's platform cap of the original owner is also temporarily retained). However their buildings and modules cannot be changed, and they cannot be upgraded or downgraded, although they can be returned back to the owner.

It's worth noting, that auto-upgrading a starbase can "gift" higher tech components to occupied starbases (including FTL inhibitors!), while keeping their own more advanced components. They will stay equipped even if said starbase is reclaimed back, so repeated re-conquering might become harder both sides.

Systems containing an unoccupied starbase or unoccupied colonized planets will not be transferred in a forced status-quo peace.

Starbase Capacity[edit]

An empire can in theory have as many starbases as their economy can support but an empire can only maintain a limited number of upgraded starbases bigger than outposts. The amount of upgraded starbases an empire can support is dictated by the Starbase Capacity and exceeding that capacity will cause all upkeep costs for starbases to increase by +25% Upkeep Upkeep for every starbase exceeding the cap. This is an empire-wide modifier, and thus affects all starbases owned by the empire. This modifier also affects the maintenance of any modules and buildings on the starbases. Regardless of their level, each starbase bigger than an outpost occupies only one capacity slot and if the need arises, an empire can always downgrade existing starbases back to outpost level to reduce the amount of upgraded starbases to within the cap limit.

The base Starbase Capacity is 3, which can be increased by the following:

  • +1 for every 10 systems owned by the empire
  • +2 Menu icon traditions.png adopting the Supremacy tradition tree
  • +2 Tech galactic ambitions.png Galactic Ambitions technology
  • +2 Tech manifest destiny.png Manifest Destiny technology
  • +4 Civic trading posts.png Trading Posts civic
  • +5 Ap reach for the stars.png Grasp the Void ascension perk
  • +10 Mod shroud unavailable.png Covenant: End of the Cycle
  • +1 Tech repeatable improved starbase capacity.png Interstellar Expansion repeatable technology
  • +2 for each Strategic Coordination Center level


A starbase is auto-fitted with the latest components as soon as they are available to the empire. This is done automatically and has no additional cost for the empire - as such this also does not affect a starbase's level upgrade cost.

The weapon slots are fitted with the most effective kinetic and energy weapons (though not necessarily by equal division). The utility slots are divided equally between Shield shield and Armor armor components (auto-fitting does not add hull components here), while the auxiliary slot uses standard auto-fitting of a shield capacitor or auxiliary fire-control (whatever is available in order of priority).

Upgrading a starbase can only be done in a sequential order - meaning that if one were start with a basic outpost and wants to upgrade it to a citadel, they have to go through every single level in between in order to get to the desired level. Downgrading a starbase, however, reduces its level to the basic outpost level (outpost) straight away - regardless of what level the starbase initally was - and removes any present buildings, modules, and any defense platforms over the outpost's capacity limit. Any resources invested into the starbase prior to downgrading will not be refunded.

Starting from the starport level all starbases can repair docked ships (regardless of whether or not it has a shipyard onboard) and have an FTL inhibitor FTL inhibitor onboard if technology is available.

Note: The table lists the base properties of each starbase level. The actual values themselves will differ due to one's progress in-game (technology, tradition, and etc.), existing modifiers (if any) as well as individual starbase composition (buildings, modules, and etc.).

Starbase Level Cost Slots Military properties Requirements Description
Alloys.png Time Upkeep M B D Health Armor Weapons Utilities
Tech starbase 1.png Outpost 0 100 100 1 0 0 3 5000 1000 Guided 1 Large 2
Auxiliary 1
Influence.png 75 Influence per hyperlane jump from closest owned system The most basic kind of Starbase, Outposts are lightly-armed stations built in stellar orbit to extend national borders. Outposts can not support any Buildings or Modules and are not listed in the Outliner.
Tech starbase 2.png Starport 1 200 360 2 2 1 6 10000 2000 Medium 2
Guided 1
Large 6
Auxiliary 1
Spaceport 1.png Outpost Upgrading the Outpost, Starports can house one Building and support two Modules.
Tech starbase 3.png Starhold 2 500 720 3 4 2 9 20000 5000 Medium 4
Guided 1
Large 10
Auxiliary 1
  • Tech starbase 3.png Starhold
  • Spaceport 1.png Starport
Upgrading the Starport, Starholds can house two Buildings and support four Modules.
Tech starbase 4.png Star Fortress 3 1250 1080 4 6 3 12 40000 10000 Medium 6
Guided 1
Large 14
Auxiliary 1
  • Tech starbase 4.png Star Fortress
  • Spaceport 1.png Starhold
Upgrading the Starhold, Star Fortresses can house three Buildings and a full complement of six Modules.
Tech starbase 5.png Citadel 4 3500 1440 5 6 4 15 80000 20000 Medium 12
Guided 1
Large 26
Auxiliary 1
  • Tech starbase 5.png Citadel
  • Spaceport 1.png Star Fortress
Upgrading the Star Fortress, Citadels are the largest and most heavily fortified type of Starbase and can house four Buildings and a full complement of six Modules.

Affecting modifiers[edit]

Additional modifiers which affect various starbase parameters are summarized below:

Construction and maintenance modifiers
Influence.png Outpost influence cost
−50% Civic devouring swarm.png Devouring swarm
−40% Fanatic Xenophobe.png Fanatic xenophobe
−30% Civic machine terminator.png Determined exterminator
  • Xenophobe.png Xenophobe
  • Ap interstellar dominion.png Interstellar Dominion
−15% Trait ruler expansionist.png Expansionist
−10% Tradition expansion reach for the stars.png Reach for the Stars
Cost Outpost build cost
−15% Trait ruler expansionist.png Expansionist
Upkeep Upkeep cost
−20% Tradition expansion galactic ambition.png Galactic Ambition
+25% "Exceeding starbase capacity" modifier
Upgrade related modifiers
Cost Upgrade cost
−33% Tradition supremacy great game.png The Great Game
−15% Tech space defense station improvement.png Corps of Engineers
  • Trait ruler fortifier.png Fortifier
  • Trait ruler home in the sky.png Home in the Sky
Speed Upgrade speed
+100% Menu icon policies and edicts.png Fortress Proclamation
+25% Tech space defense station improvement.png Corps of Engineers
Military properties related modifiers
Damage Damage
+25% Ap eternal vigilance.png Eternal Vigilance
+20% Tradition supremacy great game.png The Great Game
Health Hull points
+25% Ap eternal vigilance.png Eternal Vigilance
  • Spaceport 1.png Gun Battery
  • Spaceport 1.png Hangar Bay
  • Spaceport 1.png Missile Battery
Armor Armor hit points
  • Spaceport 1.png Gun Battery
  • Spaceport 1.png Hangar Bay
  • Spaceport 1.png Missile Battery


A fully upgraded starbase can support up to 6 modules. It is possible to construct multiple modules of the same type and the starbase will be called in the outliner accordingly.

Cost Modifiers affecting module build cost include:

  • −25% Tech modular engineering.png Modular Engineering
  • −20% Trait ruler home in the sky.png Home in the Sky
  • −10% "Zero-G Innovations" modifier
Module Alloys.png Cost Time Time Upkeep Upkeep Effects Requirements Description
Sb shipyard.png Shipyard 50 180 1 +1 Shipyard capacity increase A Shipyard may build one ship at a time, in parallel with other Shipyards.
Sb anchorage.png Anchorage 50 180 1 Mod fleet size add.png +4 Naval capacity Fleet anchorages are necessary to support the growth of our navy.
Sb gun battery.png Gun Battery 50 180 1
  • Medium +2 Medium weapon components
  • Trade protection.png +5 Trade Protection
  • Shield +1 Protection Range
  • Yes.png Starbase and platforms gain:
  • Armor +10% Armor hit points
  • Health +10% Hull points
Adds two medium-size weapon slots to the Starbase.
Sb missile battery.png Missile Battery 50 180 1
  • Guided +2 Guided weapon components
  • Trade protection.png +5 Trade Protection
  • Shield +1 Protection Range
  • Yes.png Starbase and platforms gain:
  • Armor +10% Armor hit points
  • Health +10% Hull points
Adds two torpedo weapon slots to the Starbase.
Sb hangar bay.png Hangar Bay 50 180 1
  • Hangar +1 Hangar weapon components
  • Trade protection.png +10 Trade Protection
  • Shield +1 Protection Range
  • Yes.png Starbase and platforms gain:
  • Armor +10% Armor hit points
  • Health +10% Hull points
Tech strike craft 1.png Carrier Operations technology Adds a hangar for strike craft to the Starbase.
Sb trading hub.png Trade Hub 50 180 1 Mod starbase trade collection range add.png +1 Collection Range No.pngGestalt consciousness.png Gestalt Consciousness A civilian docking area where merchants and traders can conduct business.
Solar Panel Network.png Solar Panel Network 50 180 Energy Credits.png +3 Energy Gestalt consciousness.png Gestalt Consciousness Advances in solar panel technology cound offset the operating costs of our starbases.


A fully upgraded starbase can support up to 4 buildings. Unlike modules, it is only possible to construct a single building of any type. Building cost is reduced by −25% by the Tech modular engineering.png Modular Engineering technology.

Building Alloys.png Time Upkeep Effects Requirements Description
Sb artist college.png Art College 200 360 2 +10 Unity.png Unity
  • Diplomacy alliance.png A diplomatic agreement with the in-system Artisan enclave
  • No.png Is not:
  • Gestalt consciousness.png Gestalt Consciousness
  • Civic fanatic purifiers.png Fanatic Purifiers
This zero-g Art College, operated in conjunction with the nearby Artisan Enclave, celebrates the beauty of outer space in the works produced by its talented students.
Observatory.png Black Hole Observatory 100 360 2 +10 Physics Research Physics research
  • Tech sensors 3.png Subspace Sensors
  • Black Hole.png System contains a black hole
By building a specialized science facility dedicated to studying a black hole, our empire will surely be able to see improvements in our understanding of Physics.
Sb colossus assembly yard.png Colossus Assembly Yards 1000 720 20 Ap colossus project.png Colossus construction enabled in Shipyards
  • Tech colossus.png Colossi
  • Spaceport 1.png Citadel
  • Spaceport 1.png Shipyard
Abandoning the traditional concept of drydocks, Colossi are assembled by a number of highly mobile independent construction platforms.
Sb command center.png Command Center 250 360 5
  • Defensive aura:
  • +10% Mod ship fire rate mult.png Fire Rate
  • Tech doctrine command matrix.png Command Matrix
  • Spaceport 1.png Star Fortress
All system defense efforts are coordinated from this large facility, buried deep within the hull of the Starbase. Map arrays and 3D projections track all space traffing passing through the system at any given time.
Sb communication jammer.png Communications Jammer 50 180 1
  • Offensive aura:
  • –20% Mod ship disengagement.png Combat disengagement chance
  • –20% Mod ship speed mult.png Sublight speed
These powerful jammers interfere with enemy ship-to-ship communications, making it difficult to coordinate fleet movements.
Crew Quarters.png Crew Quarters
Gestalt consciousness.png Crew Gestation Chambers
50 180 1 –25% Mod ship upkeep mult.png Docked ship upkeep Provides accommodation and support for spaceship crews, reducing the logistical burden on fleets that are berthed here.
Gestalt consciousness.png The ability to birth and gestate crew drones directly on-site is a logistical boon to local fleets.
Sb curator think tank.png Curator Think Tank 100 360 2 +5 Research.png Research
  • Diplomacy alliance.png A diplomatic agreement with the in-system curator enclave
  • No.pngCivic fanatic purifiers.pngCivic devouring swarm.pngCivic machine terminator.png Genocidal
By constructing a research facility entirely focused on learning from, and cooperating with, the Curators, we are able to make significant contributions to our scientific progress.
Sb deep space black site.png Deep Space Black Site 100 360 2
  • +1 Unity.png Unity
  • Yes.png System gains:
  • +25% Mod pop government ethic attraction.png Governing ethics attraction
  • +5 Stability.png Stability
  • Tech living state.png The Living State
  • Yes.png System is colonized
  • No.pngGestalt consciousness.png Gestalt Consciousness
A large part of this Starbase has been set aside as a Black Site that does not officially exist. The entire system is closely monitored from here, while intelligence operatives carefully manipulate local media and social events to the best of their ability.
Sb defense grid supercomputer.png Defense-Grid Supercomputer 150 360 2 +8 Mod starbase defense platform capacity add.png Defense Platform Capacity Tech synchronized defences.png Synchronized Defenses A powerful supercomputer coordinating the relative orbit and firing arcs of the Starbase's defensive platforms, increasing the number of defensive platforms that can be supported.
Sb disruption field generator.png Disruption Field Generator 100 180 2
  • Offensive aura:
  • –20% Shield Shield hit points
Generates localized fields of agitated subatomic particles around hostile ships in the system, significantly reducing the effectiveness of their shields.
Fleet Academy.png Fleet Academy
Gestalt consciousness.png Battle Simulators
100 360 2 +100 Mod leader species exp gain.png Ship starting experience
  • Tech interstellar fleet traditions.png Interstellar Fleet Traditions
  • Spaceport 1.png Shipyard
For our newly recruited crews to be truly combat ready, they must have capable officers leading them. The Fleet Academy will ensure those officers have up-to-date knowledge on the doctrines and practice of interstellar warfare.
Gestalt consciousness.png Repeated simulation of various battle scenarios will better prepare our shipboard combat drones for real combat.
Sb hydroponics bay.png Hydroponics Bay 50 180 1 +3 Food.png Food Hydroponic Farming Tech By dedicating a section of this Starbase to Hydroponic farming, the station will be able to feed itself and even export excess produce to other systems.
Sb hyperlane registrar.png Hyperlane Registrar 100 180 2
  • Defensive aura:
  • +20% Combat disengagement chance
  • –20% Jump charge time
  • –20% Jump cooldown
Tech hyper drive 2.png Hyperlane Breach Points Assists friendly ships in the system with FTL travel by identifying ideal conditions for entering the hyperlanes and optimizing projected travel routes.
Sb listening post.png Listening Post 100 360 2 +2 Mod planet sensor range mult.png Sensor Range
+4 Mod planet sensor range mult.png Hyperlane detection range
Tech sensors 2.png Gravitic Sensors The Listening Post houses a team of dedicated operators tasked with analyzing hyperlane reverberations, functionally extending the range of the Starbase's sensors.
Sb nebula refinery.png Nebula Refinery 100 360 2 +6 Minerals.png Minerals
  • Tech mineral purification 1.png Mineral Processing
  • Yes.png System is inside a nebula
By processing the dust clouds of a nebula, we are able to refine and extract valuable minerals.
Sb offworld trading company.png Offworld Trading Company 100 360 0 +2 Trade value.png Trade Value from Spaceport 1.png Trading Hub
  • Tech space trading.png Space Trading
  • No.pngGestalt consciousness.png Gestalt Consciousness
  • Spaceport 1.png Trading Hub
The offices of a non-governmental organ dedicated to improving the conditions of interstellar trade.
Sb resource silo.png Resource Silo 50 180 0
  • +2000 Mod country resource max add.png Resource Storage Capacity
Massive resource silos and energy storage facilities where large quantities of minerals and energy can be safely kept.
Sb titan assembly yard.png Titan Assembly Yards 500 720 10 Feature Titan construction enabled in Spaceport 1.png Shipyard
  • Tech titans.png Titans
  • Spaceport 1.png Citadel
  • Spaceport 1.png Shipyard
Specialized drydocks erected on the Starbase's hull allow for the construction of gargantuan Titan-class ships.
Sb offworld trading company.png Trader Proxy Office 100 360 0 -5% Navbar icons market.png Market fee
  • Yes.png System has Trader enclave
  • No.png Is not:
  • Gestalt consciousness.png Gestalt Consciousness
  • Civic fanatic purifiers.png Fanatic Purifiers
The Trader Enclave enjoy special privileges on the Galactic Market, which can also benefit us.

Defense platforms[edit]

Mammalian Ion Cannon

A starbase's self-defense capabilities can be further reinforced with the construction of defense platforms. These platforms are smaller military stations deployed around the starbase. They will engage any incoming hostile forces, effectively acting as a buffer, by attacking and distracting them from focusing their efforts on the starbase itself. When compared with ships, platforms are situated between destroyer and cruiser classes, their hull and armament slightly better than the first, while armor-potential is equivalent to the latter. However, due to them having no evasion whatsoever, individual platforms are still very vulnerable, and if a strong, sustainable firepower is a priority it is wiser to put more turrets on the base itself.

As opposed to the auto-fitting of the starbase's components, defense platforms can be altered through the ship designer allowing for several designs to be built based on the different needs in each front and upgraded based on this designs. However, unlike ships, their designs cannot be switched once built, necessitating dismantling and complete rebuilding. It also renders any transferred platforms non-upgradeable. Economically defense platforms are, again, comparable to destroyers, but they cost no minerals upkeep.

Each starbase can support only a certain number of defense platforms based on its level. However, the defense platform capacity can be increased with the following:

  • Globally: +5 Ap eternal vigilance.png Eternal Vigilance, +4/+8/+12 Tech mega engineering.pngStrategic Coordination Center galatic wonder
  • Locally: +8 Spaceport 1.png Defense-Grid Supercomputer
Defense platform modifiers

Additional modifiers which affect various defense platform parameters are summarized below:

Damage Damage
  • Ap eternal vigilance.png Eternal Vigilance
  • Agenda Secure the Borders
+10% Tech repeatable improved military station damage.png Synchronized Firing Patterns
Health Hull points
+25% Agenda Secure the Borders
  • Tech repeatable improved military station health.png Fortified Core Layers
  • Spaceport 1.png Gun Battery
  • Spaceport 1.png Hangar Bay
  • Spaceport 1.png Missile Battery
+500 Tech defense platform hull 1.png Improved Structural Integrity
Armor Armor hit points
  • Spaceport 1.png Gun Battery
  • Spaceport 1.png Hangar Bay
  • Spaceport 1.png Missile Battery
Cost Build cost
−33% Trait ruler fortifier.png Fortifier
−15% Agenda Secure the Borders
Speed Build speed
+100% Menu icon policies and edicts.png Fortress Proclamation


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