Isaac Arthur - O'Neill Cylinders
We currently have ringworlds, which we can find randomly spread out across the galaxies. But they can't have been the only mega-structures that survived the test of time.
I simply propose O'Neill Cylinders as a new rare planet type. Allowing them to rarely spawn in place of planets. Or rarely a system could have no planets and instead have a number of O'Neill Cylinders orbiting the star, similar to a ringworld system.
Since they are kinda an inverted world, landing a spacecraft in them is the biggest issue I see. Either they are so big that a spacecraft can fly in through holes in the ends of the cylinder and land like normal, or they only allow you to get in via external docking ports with turbo lifts that take you inside.
What do you guys think? How do you think O'Neill Cylinders could work in Hazeron? Would they even have a use?