Faction bases are sites where factions settle. This feature was first seen in Alpha 16, where rudimentary bases were generated. Both enemy and friendly factions alike can be raided by your colonists, upon which a map for the encounter will be created.
Faction bases consist of random constructs, all surrounded by sandbags.
As of Alpha 17 they now utilize power and can have turrets, or the occasional mortar. Bases are also more well-designed. The game uses a "grammar system" that incorporates indoor and outdoor parts in order to generate a base. The following components may show up as part of a faction base, and can be found in the developer tools under "Tool: BaseGen."
Indoor and Outdoor Areas
Indoor rooms are spawned as one large interconnected area. Outdoor areas will still have indoor rooms, although rooms may spread out with exposed walkways between. Light sources and power appear depending on faction type, with standing lamps used by more advanced factions and tribals dependent on torches and passive coolers. Tribal walls are made of wood, whereas other factions make use of stronger walls.
Upon entering the site, all indoor areas are hidden until player pawns enter.
A room full of batteries, neatly spaced. These are exclusive to non-tribal factions.
An outdoor farm plot consisting of a single plant type and sometimes an indoor 2x2 stockpile of the plant matter in the corner.
Non-tribal factions make use of perimeter sandbags, improvised turrets, and even mortars. Once defeated, a base's turrets can be safely claimed to disable firing at friendly pawns and even turn them to your side, shooting at escaping hostiles.
These can be uninstalled and brought back to your colony, though it is not recommended due to their heavy weight.
Enemies will spawn in the base hostile to player pawns. If unspotted, they will not attack immediately. However, once someone gets killed or downed, the enemy will immediately notice and will proceed to charge towards your attackers.
Similar to raids, once a threshold of the enemy has been defeated, they will flee and abandon their base, upon which the player will be able to claim the faction base as their own. After 24 hours, the player must reform the caravan and leave the site.
For friendly bases you can send a caravan to visit it instead, opening the opportunity to trade.
Faction bases have an extensive inventory consisting of most item categories, and they buy most items.