One of the key things in Lord of Rigel are star systems and their planets. So how do we generate them? The first part is based on star type. Each stellar category (Blue, White, Yellow, Orange, Red, Brown Dwarves, White Dwarves, and Neutron Stars) changes the number of orbits that a system will have and the potential planet types in an orbit. Part of this is a random roll, which is weighted by the star type.
Each system has a few satellite types that can fill an orbit. These include Planets, Asteroids, Gas Giants, and Stars. There’s a set probability for satellite types per orbit. Basically, stars are common in inner and outer orbits; asteroids are frequent in middle orbits, and gas giants more common in outer orbits, but can be present in close orbits too.
For planets, there’s then a set of environmental categories for each spectral class (star type) and orbit. These categories include Bombarded, Hostile, Life Supporting, and Lifeless. Each of those categories has a weighted probability for what types of planets spawn there. Life supporting orbits tend to have Earth like worlds while Bombarded orbits will have Radiated, Inferno, or Toxic planets.
Once we get to this stage, planets are spawned with their climates. We then do a random roll to determine planet size (tiny to huge). There’s also another die roll for mineral content (Ultra-poor to Ultra-rich) which is also weighted by star type. Overall star types that are more conducive to life (Yellow, Orange) tend to have poorer minerals while hotter star types (Blue, White) have more minerals. Stellar remnants (white dwarves, neutron stars) tend to be ultra-mineral poor. Planet size and mineral content are then taken into account to determine a planet’s gravity type. Small, mineral poor planets have low gravity while large, mineral rich ones have high gravity. Planet size and climate determines maximum population.
Overall, these systems come together to determine population, production, and farming on each planet. Climate mostly impacts maintenance costs and food. Minerals affect the production amount, while gravity impacts both food and production. Finally, there’s at least a 25% chance that a system will have some sort of special; the chance is higher for brown dwarves, white dwarves, and neutron stars. There’s a good chance that a system special will be a planetary one, applied to a random planet in the system. These bonuses can range from a world being fertile to having a native population. Generally if a planet has a special, it’ll be converted to a Terran or Gaia type world.
That covers the basics of star system generation in Lord of Rigel. It’s a bit of a complicated system and since the first galaxy generator demo we expanded it with additional climate types (Inferno, Jungle, Dead). But for now we have a good range of planet types that cover all of the archetypal worlds you see in science fiction!