Aether Raiders
v1.14 includes a new 'spoiler' race, known as the Aether Raiders. They are inspired by the Dark Eldar in the WH40k universe and will function as a pirate faction. High level mechanics details follow, so stop reading now if you want to avoid spoilers.
The Raiders are based in a system that has no jump points and cannot be accessed via normal travel. As a result, they developed a technology known as the Aether Gate, allowing them to create their own pathways between their home system and other systems in the galaxy. The Aether Gates are temporary energy structures, although they can exist for months or even years before they are closed down. They cannot be detected by normal surveying methods, although the sudden appearance of a raider ship within existing sensor range will be a very good guide to the potential location.
As a result of basing their technology on Aether Gate travel, the Raider ships cannot travel via jump points.
The goal of the Raiders is to accumulate slaves and raw materials. They do this by scouting out systems to find alien shipping, preferably undefended commercial shipping, or small colonies. Shipping is destroyed and colonies are captured, allowing slave transports to collect life pods or colonists and salvage ships to loot the wreckage before heading back through the gate.
The Raiders wish to preserve their forces, unless a very good opportunity is presented, so they are more likely to avoid combat with warships than NPRs or other spoiler races. Raider ships are designed with that philosophy in mind. Generally, they will operate solo or in small groups, although a larger force may be encountered occasionally.
The Raiders are not interested in capturing territory or destroying other races, so they do not pose an existential threat. However, they can prove to be very disruptive to shipping lanes and frontier colonies and their ability to open gates to any system means that they can potentially appear anywhere without warning. New Raider ships will be built over time and their technology may improve too. The individual Raider ships are tracked, so you may encounter the same ship over time in different systems. Destroying ships will reduce their forces and consequently reduce the size and/or frequency of future raids.
Raiders must exit a system via the same gate through which they entered. However, once all raiders leave a system that gate will be shut down. If Raiders return to the same system, a new gate will be opened in a different location.
Aether Raiders have been added as a option to the Game window. There is also an option to prevent them appearing in NPR-claimed systems.