The Unfallen are a tree-like species, deeply rooted (pardon the pun) in its home planet. They rely on special links (vines) between star systems to increase their territory or aid friendly and/or allied civilizations. Colonization can be accomplished only through such special links. They do not extend an influence zone around their star systems like other races do. The Unfallen depend mostly on quick population growth, which is clear once you see their traits. Another unique thing about them is the minor race of Guardians. You can find their representatives by examining Curiosities in uncharted systems. They are capable of quickly terraforming even the most hostile planetary environments, cold or hot, once you complete the quests related to their species.
Special ability. Instead of typical colonization ships, you are given special vessels that can be sent from systems already controlled by the vines. Once in a new system, the process of linking is initialized. If it gets interrupted, either by your choice or, for example, by the destruction of your ship by the enemy, the process will have to be repeated from scratch. You can also link up nebulas or asteroid belts, adding their bonuses to the bonuses of the mother system. To assimilate a minor faction, you'll also need a vine link in addition to a full relations' bar.
Faction traits. They have the ability to discover the locations of Guardians, a minor race, very important to The Unfallen. You need to colonize the planet on which you've found the Guardians to be actually able to use them. They inflict a bonus of damage in battles, planetside and in space, for each friendly faction and empire. Additionally, they provide a +8 bonus to Approval during peacetime, and +16 for each alliance with another empire.
Race traits. The Unfallen receive a +5 bonus to Food, and further +5, for a total of +10 on fertile planets. If you assemble 20 representatives, you'll receive a 15% bonus to Influence points. They are Pacifists by nature, being quite against Industrialism. You'll often encounter Guardians, a minor race providing a +5 bonus to Approval and inflicting bonus damage when defending against an invasion. The required number of representatives for collection status is smaller for this race, being 5, 10, and 20 citizens. At 10, they receive a +10 bonus to Approval, and at 20, they unlock a special act. The Guardians cannot be moved between systems and planets. They are assigned to the place in which they were discovered.
Colonization method. If the system is under the control of your vines and there are planets, which can be colonized, colonization will be instantaneous.
Basi ships. All ships of this faction have good armor. Almost all ship classes have at least 2 defensive module slots. Medium ships are characterized by a single omni slot, on which you can install any module. The downside is reduced number of weapon slots. Even their biggest ships have only 3 weapon slots (including one for heavy weapons), where other factions' ships usually have 4. The Unfallen fleet's basic tactic is to endure rather than knock out the enemy.