Ancient races

There are 3 unique Aliens species. You turn on\off all alien incursions during game creation or

Precursors

The robotic Precursors are an ancient species that dominated the galaxy until they were defeated by the Invaders. Since then, they have fallen into decay and all that remains are few isolated groups of robotic ships that guard the ruins of defeated foes waiting for new instructions that never arrive. Their mission is simply to eliminate all non-Precursor life.

The precursors did have a Jump Gate network and some of those jump gates remain. Precursors robotic ships guard some of the alien ruins and occasionally random encounters with small Precursor ships maybe created in non-ruin system. They have no real populations, although they may have small listening posts and weapon caches in the system. Although few in number and they don't have any survey ships for exploration, they are likely to be higher tech than your own Empire at game start and any starting NPRs. You will need to overwhelm, outsmart or simply avoid them until you are ready. Leave this selected as Precursors provide valuable combat experience. Rather than a complete Empire similar to your own (which is what NPRs will be).

Invaders

The menacing extra-galactic Invaders, which threaten to bring their extremely advanced technology to bear in a massive galactic purge, and already defeated the Precursors civilization during their last invasion.

They are always hostile, very high tech and extremely dangerous. For a starting game, its best to disable them so leave that box unchecked. Also beware Invaders tend to explore a lot, causing the game to become slower.

Star Swarm

The biological Star Swarm species of living ships that reproduce in space. Individually they are weak, but can be very dangerous in numbers infest any system in their way.