3.5

After completing the [Voidborn] advanced ascension, you can now choose two branches:
[City of a Thousand Stars] allows you to greatly expand the habitat, build more divisions and buildings, and at the same time increase the production of all habitats, you will be more dependent on the output of habitats.
[Void Citadel] will fortify the habitat, allow the addition of an outer ring defense system similar to the star ring, and add some new outer ring buildings. At the same time, you can build defensive platform positions in the outer ring, turning every habitat into a fortress.
Note that the outer ring added by [Void Castle] can be linked with [Magnoit Line] to further strengthen its combat effectiveness.