Back in version 0.3 I've been thinking about adding orbital habitation feature that would allow players to populate moons and even planetary orbits. For the rest of the post I'll refer to moons and orbit as just orbit. I ditched the idea because I couldn't come to terms how farming and mining should cooperate with the feature. Should there be a limit how many miners can exploit the planet, should there be penalties for transporting goods from surface to orbit (because there is such penalty when building ships). Splitting colony to two, one for each "plane", would help organize the matter but brings another question. Since surface and orbit would be very different in productivity and construction costs, should there be different building queues for each "plane"?
Firstly I'd like to add special traits to all planet types. Traits would be mainly negative stuff like acidic atmosphere (increased environment hostility), active vulcanos, large mountains (less inhabitable space). Occasional there would be positive effects such as active core (less radiation) or fertile soil.
Than I'd add moons in place of gas giants. Each gas giant would be represented with cumulative surface of it's moons and traits that partially affect colony, simulating diversity of moons. For instance Jupiter has 4 moons "worth of notice" so it would be represented with 75 size points (75% of earth sized body) with vulcanic (Io) trait that affects 1/4 of colony, water world (Europa) trait that too covers 1/4 of colony and some gas giant specific trait like cheap fuel (faster ship resupply). What partial trait coverage means is not decided yet. In the simplest case it would be simply reduced normal trait. In a more complex case it would kick in when colony starts to utilize that part of moon system. For instance Io's vulcanic trait would start affecting the colony once it's population grows beyond 75% of maximum with increasing strength as population reaches 100%. I'll decide it when I start implementing planet traits.