After just coming out of the shower, I have had an epiphany: Seismic and volcanic activity on planets. This feature would not be applied to all planets, as it may cause too much server stress. This engine would work similar to how tectonic plates work on earth, or the plates could be immobile and the only evidence that they exist is mountains and valleys.
All of the plates on Earth are driven by one thing: magma. This magma could present on planets, with unique subcrustal temperatures varying greatly. This magma does not have to be fluid, but textured to look fluid. This would ensure that server stress levels remain stable to handle this amount of liquid present without crashing. In order to compensate for this lack of fluidity, lava tubes could be implemented to present evidence of previous plate activities that could be used as a base hideout of some kind.
This magma could be used as an energy source, with many pumps being used to extract it. These tubes would have to be able to handle the high temperatures of the magma in order for successful magma extraction to happen. If it is unsuccessful, the pipes could just melt or something. This would explode the market with different types of tubes with varying effectiveness.
I will continue this post as a different idea titled "Ice Moons and Cryovolcanism" so you can respond to it separately.