Megastructures

Version

This article may contain outdated information that is inaccurate for the current version of the game. It was last updated for 2.3.

This article is for the PC version of Stellaris only.

Humanoid Empire constructing a Dyson Sphere

Megastructures are colossal constructions. Expensive and time-consuming to build or repair, these remarkable feats of engineering are nonetheless important wonders that provide large bonuses, demonstrating the technological and economic primacy of the builders' empire. All of them require unlocking certain technologies to be built.

Construction

There are three types of megastructures: gateways, habitable projects and galactic wonders. Systems can only host one galactic wonder. Habitable megastructures (habitats and ringworlds) can be colonized but will be irreparably destroyed if a crisis overruns them. Galactic wonders provide massive bonuses and cannot be destroyed by any crisis, but are limited to one per empire. All megastructures have a different textures depending on the empire that built them.

It is only possible to build, upgrade, or restore one megastructure at a time, except in the case of habitats and gateways. The limit can be increased by one with the Master Builders perk, and one more with the Architectural Renaissance Ambition edict.

A construction ship is required to build the first stage of any megastructure. If the megastructure has multiple stages, the following stages do not require the construction ship.

Each megastructure is unlocked by researching the technology of the same name. An empire that conquers a system with a megastructure can use it, but if the construction was partial it will not be able to continue its construction without the required technology. Damaged megastructures found through exploration, however, can be reconstructed by unlocking the Mega Engineering technology.

Bonuses

A few bonuses affect megastructure construction speed. These are highly desirable considering the great time requirements of such projects:

• Master Builders ascension perk increases the build speed by +50%
• Living Metal Mega-Construction edict increases the build speed by +50%
• Architectural Renaissance unity ambition also increases the build speed by +50%

Gateways

Real scale of a Gateway

While exploring the galaxy, empires can find abandoned gateways that were once part of a massive, galaxy-spanning network. Reverse-engineered from encountered abandoned gateways, these megastructures require the Gateway Activation technology and can be used to travel directly to any other active gateway in the galaxy. Reactivation of gateway takes 2 years and costs 6000 energy and 2500 alloys. The Gateway Activation technology can appear as a research option as soon as a Gateway has been discovered and Hyperspace Slipstreams technology has been researched but the chance is very low. Owning a system with an inactive Gateway increases the chance for the tech to appear by 4 times.

When the first gateway in the galaxy is reactivated, another random gateway will also be re-activated along with it. As opposed to wormholes, both gateways must be owned by the same empire or two empires with open borders in order to be able to travel through them. Systems with gateways count as bordering for the purposes of diplomacy, so every opened gate increases diplomatic tension between all active gate-owners. Claims cannot be extended through gateways. Additionally, gateways are able to greatly enhance and simplify trade infrastructure.

Eventually, empires can build their own gateways by researching the Gateway Construction technology. Notice, that this tech requires having some civilization with an access to pre-existing gateways, so if gateways were disabled during galaxy creation it is impossible to build any new. Each system can have only one gateway, but black hole systems with an L-Gate can also have a regular gateway constructed. Gateways can be built in systems in which there is already a megastructure. The construction site is built in only 3 years and costs 100 influence and 2500 alloys. Upgrading it to a gateway takes 5 years and costs 6000 energy and 2500 alloys.

Habitats

Mammalian habitat.

Artificial planets in all but name, habitats have a planet size of 6 to work coupled with 70% habitability for all species. Its appearance is dependent on the builders' empire appearance. The constructed habitat still requires colonization.

Habitats may be built over any world except a moon or asteroid. It doesn't matter if the world is colonized, but they can't be built alongside an existing mining or research station. (You can disband/dismantle the station to make the site available.)

Habitats have a unique set of Districts distinct from normal planetary ones. Up to 3 Districts are shared among all Habitats, with a fourth one being available if the Habitat is built above a planet with a resource deposit. Generator Districts are available for energy deposits, Mining Districts are available for mineral and alloy deposits (which are added as a rare feature to the habitat), and research districts become available for any celestial bodies that provide research boosts. The districts are only capped by the maximum amount of districts for that station (6 or 8, see below). Habitats built above a strategic resource allow building a Crystal Mine, Gas Extraction Well, or Mote Harvesting Trap to exploit them.

The project takes 5 years to complete and costs a total of 200 influence and 3000 alloys. Unlike other megastructures habitats do not require a construction site and are finished in one go by the construction ship.

Habitats require the Orbital Habitats technology to be built. The Voidborne Ascension Perk increases their Habitability to 90% and District Cap to 8. They cannot be built on moons or planets with an anomaly.

If a habitat is destroyed by a crisis or World Cracker it will never be possible to build another habitat on the same spot, or even a mining/research station, so any strategic resources on the planet are permanently lost.

Multi-stage megastructures

Multi-stage megastructures are constructed in multiple stages. Almost all of them can only be constructed once. They start with a construction site that provides no benefit, however each subsequent construction phase will bring increasing bonuses, culminating with the end of the megastructure construction. Habitats and gateways can be built in the same system as multi-stage megastructures.

These Megastructures can only be built once per empire and require the technology of the same name before they can be constructed. However their bonuses are massive and they cannot be destroyed, only captured.

Multi-stage megastructures conquered from other empires do not count against the build limit, nor do ruined ones that are found and repaired.

Megastructure		Production	Upkeep	Time	Cost	Notes	AP	DLC
Ring World	Site	None	-5	5 years 3.33 years	300 5 000	Cannot be built around Black Holes or in systems with multiple stars Cannot be built if there are habitable planets, anomalies or stations present Unlike other multi-stage Megastructures an empire can build more Ring Worlds All segments feature +100% Habitability for each species, can build up to 5 unique Districts and have their own unique Designations If they are built in the L-Cluster the uninhabitable segments will have Nanites deposits Upon completion of the frame all planets are removed from the system Multiple segments can be built at the same time if you have the capacity to work on more than one megastructure simultaneously
	Stage I (Frame)	None	None	13.3 years 8.88 years	10 000
	Stage II (1 Segment)	+1 Habitable Segment	None	10 years 6.66 years	10 000
	Stage III (2 Segments)	+2 Habitable Segments	None	10 years 6.66 years	10 000
	Stage IV (3 Segments)	+3 Habitable Segments	None	10 years 6.66 years	10 000
	Stage V (Complete)	+4 Habitable Segments	None	10 years 6.66 years	10 000
Dyson Sphere	Site	None	-5	5 years 3.33 years	300 5 000	Can only be constructed around regular stars Cannot be built if there are habitable planets, anomalies or stations present Upon completion all rocky planets and moons in the system turn into frozen or cold barren worlds
	Stage I (Frame)	None	None	10 years 6.66 years	10 000
	Stage II (Partial 25%)	+1000 Energy	None	10 years 6.66 years	10 000
	Stage III (Partial 50%)	+2000 Energy	None	10 years 6.66 years	10 000
	Stage IV (Partial 75%)	+3000 Energy	None	10 years 6.66 years	10 000
	Stage V (Completed)	+4000 Energy	None	10 years 6.66 years	10 000
Science Nexus	Site	None	-25	5 years 3.33 years	300 5 000	The final stage of a Science Nexus can be upgraded to produce 50 more Research through an event that has a 30% chance to trigger a short time after the Megastructure is finished
	Stage I (Hub)	+100 Research +5% Research Speed	-50	10 years 6.66 years	15 000
	Stage II (Research Wings)	+200 Research +10% Research Speed	-75	10 years 6.66 years	15 000
	Stage III (Completed)	+300 Research +15% Research Speed	-100	10 years 6.66 years	15 000
Sentry Array	Site	None	-20	5 years 3.33 years	300 5 000	Until finished the Sentry Array cannot see through nebulae
	Stage I (Sentry Hub)	+20 Hyperlane Scanner Range	-40	5 years 3.33 years	10 000
	Stage II (Sentry Spire)	+40 Hyperlane Scanner Range	-60	5 years 3.33 years	10 000
	Stage III (Sentry Aerials)	+60 Hyperlane Scanner Range	-80	5 years 3.33 years	10 000
	Stage IV (Completed)	Entire Galaxy Hyperlane Scanner Range	-100	5 years 3.33 years	10 000
Matter Decompressor	Site	None	-5	5 years	300 5 000	Can only be constructed around black holes
	Stage I (Anchor)	+500 Minerals	-25	10 years	12 500
	Stage II (Lensing)	+1000 Minerals	-50	10 years	12 500
	Stage III (Boring)	+1500 Minerals	-75	10 years	12 500
	Stage IV (Completed)	+2000 Minerals	-100	10 years	12 500
Mega Art Installation	Site	None	-5	5 years	300 5 000	The final stage requires the Ancient Relics DLC and is not available if the empire is Xenophobe or Fanatic Xenophobe
	Stage I (Nascency)	+100 Unity +5% Amenities	-10	10 years	15 000
	Stage II (Maturity)	+200 Unity +10% Amenities	-20	10 years	15 000
	Stage III (Completed)	+300 Unity +15% Amenities	-30	10 years	15 000
	Stage IV (Perfection)	+400 Unity +20% Amenities	-30	10 years	100
Strategic Coordination Center	Site	None	-5	5 years	300 5 000
	Stage I (Hull)	+50 Naval Capacity +2 Starbase Capacity +4 Defense Platforms +5% Sublight Speed	-25	10 years	15 000
	Stage II (Comms)	+100 Naval Capacity +4 Starbase Capacity +8 Defense Platforms +10% Sublight Speed	-50	10 years	15 000
	Stage III (Completed)	+150 Naval Capacity +6 Starbase Capacity +12 Defense Platforms +15% Sublight Speed	-75	10 years	15 000
Interstellar Assembly	Site	None	-5	5 years	300 5 000
	Stage I (Locus)	+10 Other Empires' Opinion +25% Immigration Pull	-10	5 years	10 000
	Stage II (Consul Ring)	+20 Other Empires' Opinion +50% Immigration Pull	-20	5 years	10 000
	Stage III (Forum Modules)	+30 Other Empires' Opinion +75% Immigration Pull	-30	5 years	10 000
	Stage IV (Completed)	+50 Other Empires' Opinion +100% Immigration Pull	-40	5 years	10 000

Ruined megastructures

Ruined Dyson Sphere

A ruined version of a multi-stage megastructure can be found while exploring the galaxy, with the largest galaxies having a chance to spawn two or even three systems with ruined megastructures. Repairing them only requires the mega-engineering technology and no ascension perks. If not yet researched, running into a ruined megastructure also grants a better chance for mega-engineering to appear as a researchable technology.

While they upgrade from their broken to a fully functional state in one step, they do not count for any achievements. However, they do not count against any build limit for that particular megastructure either. Another megastructure may also be constructed in the same system as a ruined or restored one.

Ruined Megastructure	Time	Alloys
Dyson Sphere	7200	20000
Science Nexus	4800	15000
Sentry Array	4800	15000
Matter Decompressor	4800	20000
Mega Art Installation	4800	20000
Strategic Coordination Center	4800	15000
Interstellar Assembly	3600	15000

Conquerable Ringworlds

Up to 7 ringworlds can spawn naturally in a game in various states. Damaged segments can be repaired with the mega-engineering tech for the same cost as finishing a new segment.

• 1 in the Sanctuary system. All 4 habitable sections are intact and each contains one pre-FTL civilization, none advanced beyond Steam Age. The system was abandoned by an Enigmatic Observer Fallen Empire but contains automated defense platforms totaling over 50k fleet power.
• 1 in the Cybrex Alpha system. It requires completing the Cybrex precursor event chain. The ringworld is completely ruined and requires repairs on each section.
• 1 in the Cybrex Beta system. It will only be revealed if the Contingency sterilizes 20% of the galaxy. A short time after the Contingency is defeated, the Cybrex will leave the galaxy, leaving the ringworld free for the taking.
• 1 in a random empty system if Utopia DLC is activated. It is completely ruined and each section requires repairing. If the Distant Stars DLC is activated as well the system can contain an unique anomaly.
• 3 in the systems of the Ancient Caretakers if Synthetic Dawn DLC is activated. The ringworld in the home system has 3 intact and one ruined section while the other two ringworlds are completely ruined and require each section to be repaired separately.

Game concepts