Spacemen, as it is now, is a sand-box 4X game placed in a procedural persistent universe.
This means that in the beginning there are no sectors generated in the universe. First time the player attempts to explore one nearby sector, this will be randomly generated if not previously visited. When a new sector is generated, firstly the sun type is randomly decided and based on the sun size and gravity, there are a number of planets added.
The planet type is decided based on the distance to the sun. If the planet is in the habitable zone of the sun, the new planet may contain an ocean and may sustain life. The aspect of the planets and resources are decided, again, procedural based on the type (template) of the planet. Of course the sector is persistent, so next time the player visits it, it will be the same. Gravity of the planets and sun, as well as the temperature of the atmosphere (if present) are also calculated procedural.
Depending on nearby sectors, the new generated sector can be populated by a known or a new faction. If a faction is generated, the new faction will also be random, following faction templates. These templates decide the faction focus: social, economic, military and science. Also, the artistic style of the faction is decided based on the template.
Inside each faction, driven by its own AI, stations and buildings are built, population grows or dies, pilots trade or fight. Even mercenaries and missions are available for the player and you guessed it, it's procedural. This is the way that Spacemen generates unique sectors, planets, suns, factions each time and this will ensure the diversity of each game.