The first expansion to Rimworld added the Shattered Empire who can reward you by giving you psylinks that allow you to gain and improve your mental powers through meditiation and gain new abilities that can cause a variety of positive things, however, they will become more lovers of the fine things in life as they climb the hierarchy of nobility. Requiring lavish and expensive throne rooms and bed rooms the higher up the rank they go, but also gain favour that can be used to call in resources, mercenaries and other things. Including a free ride off the planet creating a new potential game-ending path for you to take.

They also brought in the "Anima Tree" which allows tribals to meditate and gain these psycasts through maintenance of the tree and growing more and more anima grass around this tree, making it extremely important to defend for the tribe as when it's destroyed, it creates a psychic wail, causing great negative impact to everyone on the map, regardless of how it was destroyed.

Of course, you can remove the empire if you don't want them in your game, much like you can disable any group when you want to add DLC, Mods or other such groups that either don't fit in to the kind of game you want to play or they might turn out to be extremely over-powered.

Just a bit of my gameplay below: https://youtu.be/dfkEPMPItSo