This article is for the PC version of Stellaris only.
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 or perks to be built.
There are three types of megastructures: gateways, habitable projects and galactic wonders. Systems can only host one megastructure (Unless its a habitat), except for gateways, which can be built in systems where there is already a megastructure. 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.
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.
Unlocking new megastructures
Except for gateways, ascension perks are required to unlock the ability to build new megastructures. 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 ascension perk. Damaged megastructures found through exploration, however, can be reconstructed by unlocking the Mega Engineering technology. The following ascension perks allow for the construction of megastructures:
|Ascension perk||Technology requirements||Unlocks|
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%
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 6 000 energy and 2 500 alloys.
When the first gateway in the galaxy is re-activated, 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. Gateways of opposing empires are unusable during war, even when the system is occupied. However, 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 2 500 alloys. Upgrading it to a gateway takes 5 years and costs 6 000 energy and 2 500 alloys.
Some Black Hole systems are home to L-Gates. These heavily modified gateways cannot be activated with the Gateway Activation technology. Upon first encountering one, the L-Cluster entry will be added to the Situation Log, requiring the collection of 7 L-Gate Insights. Insights can be obtained from investigating anomalies, defeating certain enemies, researching the rare L-Gate Insight repeatable Voidcraft technology or asking the Curator Order for an insight every decade (-5000 Energy).
Once 7 L-Gate Insights have been collected, the technology L-Gate Activation will become available for research. The empire will have to own a system with an L-Gate before it can access the L-Cluster. Finally, a special project will be added to activate the L-Gate, taking 180 days for a science ship to open the gate.
Opened L-Gates grant access to the L-Cluster, a cluster of stars located north-east of the galaxy and entirely inaccessible through the regular hyperlane network or experimental subspace navigation and too far for Psi Jump Drive range. The L-Cluster contains a unique Strategic Resource: Nanites. If a ringworld is built inside the L-Cluster, then while its construction will remove the planets in the system and make the original resources unavailable, the uninhabitable sections of the ringworld will contain some of the the resources instead as the habitable sections are completed, sometimes more than there were originally.
Once the first L-Gate is activated one of four things will be found, with the following weights:
|Outcome||Weight||Opens all L-gates|
The outcome is rolled at the start of the game so reloading a previous save will not alter the result.
Up to 10 L-Gates can exist in a galaxy and new ones cannot be constructed. Only one L-Gate is located in the L-Cluster, in the Terminal Egress system, and as a result any L-Gate in the galaxy will connect to the same gate in Terminal Egress but the Terminal Egress gate can be used to travel to any L-Gate inside the galaxy.
|Available only with the Utopia DLC enabled.|
Artificial planets in all but name, habitats have a planet size of 6 (unless the owner has the Master Builders ascension perk, in which case the habitat will have a planet size of 8 ) to work coupled with 100% habitability for all species. Its appearance is dependent on the builders' empire appearance. The constructed habitat still requires colonization.
Habitats have a unique set of districts distinct from normal planetary ones.
The project takes 5 years to complete and costs a total of 200 influence and 3 000 alloys. Unlike other megastructures, habitats do not require a construction site and are finished in one go by the construction ship.
Habitats require the Voidborne ascension perk to be built. 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.
|Available only with the Utopia DLC enabled.|
Immense in both radius and scope, ringworlds encircle their system's star and award their owner four ringworld sections when fully constructed. The carefully designed ecosystems and finely-tuned atmospheres of their sections offer perfect living conditions towards all residing species, granting inhabitants 100% habitability on the ring world's surface.
Ringworlds do not have planetary features like regular planets, and their planet art resembles that of Gaia worlds. Unlike habitats, they use the normal building and district set. Ringworlds are limited to City, Agriculture and Generator Planetary Districts, with a limit of 50 per section for a total of 200 per completed ringworld.
The project takes 58.33 years to complete and costs a total of 300 influence and 55 000 alloys. With the Master Builder ascension perk it takes 38.88 years instead. However, because each section is built separately after the completion of the frame, the Ringworld can be a valuable and productive asset long before its completion.
The initial site is built by a construction ship around the star, and cannot be begun if another construction ship is building a megastructure or if the system contains habitable planets. Once the site is complete, the subsequent sections built without the need for a construction ship.
Ringworlds cannot be built around black holes or in systems with multiple stars. All planets in the system are consumed upon the completion of the frame. As habitable sections of the ringworld are completed, additional, uninhabitable sections will also appear in the spaces between them. These serve little purpose except if the ringworld is built in the L-Cluster, in which case they can be mined for the unique Strategic Resources present in the cluster.
|Site||-5|| 5 years
|Frame||None|| 13.3 years
|Completed Section (x4)||None|| 10 years
|Total Cost||None|| 58.33 years
800 (site upkeep)
The following events can take place while constructing a ringworld:
- Favorable leadership conditions increase the building speed by 20%.
- A mineral deposit is discovered and you are given the option to halt construction for 20 days to get 500 alloys or proceed with the schedule.
- A number of workers might go missing, delaying the construction for a month. Two months later it will be revealed that one of the planets used in the construction had a species of furry worms the workers have grown fond of. You are given the option to either exterminate them and delay construction for a month or allow them on the building site. Whatever choice is made a month later the worms will be found feeding on the missing workers underground and be exterminated.
- Another empire might contact you, thinking that you are making weapons of mass destruction on your ring world. They will want to inspect the ring world. If you accept the request the construction will be halted and the empire gets the Request accepted opinion modifier (+40 opinion, -2 yearly). If you declined they get the Request refused modifier, with a penalty of -40 opinion.
- Another empire can contact you, asking you to allow them to base a group of researchers on your ringworld. If accepted, no time delay will occur, and after a period of time has elapsed (approx. 31 days from acceptance) you will receive 250 engineering points. The empire asking will be a fanatic egalitarian and may be on any diplomatic relation level with your empire. There is a Request accepted opinion modifier (+40 opinion, -2 yearly).
- 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.
- 3 in the systems of the Ancient Caretakers. 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.
- 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.
Given sufficient resources to construct them, habitats allow even a compact empire to rapidly grow its population, as any number of habitats may be constructed at a time, they can be constructed around a wide variety of celestial bodies, and their buildings are relatively quick to set up. Since research and unity penalties scale towards empire sprawl rather than number of colonies, they are highly efficient for tall empires, as Habitat districts provide a larger amount of housing and jobs compared to regular planet districts. Gestalt Consciousness empires can build housing buildings on habitat, further improve its performance.
Ringworlds cost 45% less alloys per district than habitats (275 for ringworlds vs 500 habitats), but 95.5% less influence (1.5 for ringworlds vs 33.33 for habitats). This calculation changes slightly with the Master Builders ascension perk due to the increased size of habitats (from 6 to 8 districts). In this case, Ringworlds cost 27% less alloys per district than habitats (275 for ringworld vs. 375 habitat), and 94% less influence (1.5 for ringworld vs. 25 for habitats).
Ringworlds can only be constructed one at a time, and their superlative size greatly increases the empire sprawl, but it serves as an ideal place for mass-producing Energy Credits and Food since ringworld section has no deposit limit. Since they consume all planets in their system when built (other than the star), it is generally recommended to construct them in systems that are poor in natural resources. If an empire has no influence banked and earns 5 influence per month, it will take 1 200 days to earn enough influence to build a habitat which is the same amount of time it takes to build the habitat with the Master Builders ascension perk. Under the same conditions, a ring world may be started every 1 800 days, but allows for a construction that takes 21 000 days (or 14 000 days with the Master Builders ascension perk) and only one section can be built at a time. This means that for maximum expansion speed, one should alternate the construction of ringworlds with that of habitats.
These megastructures require the Galactic Wonders ascension perk and each can only be built once per empire. However their bonuses are massive and they cannot be destroyed, only captured. Habitats can also be built in the same system as Galactic Wonders. Galactic Wonders cannot be built if there is an existing orbital station (mining/research station), however they can be built around secondary and tertiary stars in multi-star systems. Each Galactic Wonder starts 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.
Galactic Wonders conquered from other empires do not count against the build limit, nor do ruined ones that are found and repaired.
Ruined Galactic Wonders
A ruined version of a Galactic Wonder can be found while exploring the galaxy, with the largest galaxies having a chance to spawn two or even all three ruined Galactic Wonders. Repairing them only requires the mega-engineering technology and no ascension perks. If not yet researched, running into a ruined Galactic Wonder 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.
|Mega Art Installation||4800||20000|
|Strategic Coordination Center||4800||15000|