I'm going to necro this topic a bit, as I have something new to add.
Something new to add
This will not work on mobile.
It should work on phones now. I know it's ugly, but I only made it over the weekend, so it's still a bit rough around the edges.)
Green are miners. They collect ore from asteroids and deposit it at stations.
Blue are traders. They take the ore from the stations and sell it at planets. The planets take the raw materials and turn it into consumer goods and industrial goods. Some of these are purchased by traders to carry to other planets and stations.
Planets require consumer goods to maintain higher levels of population. One unit of consumer goods sustains ten population. Planets can normally have up to twice the population of stations.
Red units represent fighters and other fleet ships. Normally they patrol the border of their territory and perhaps go on small missions within their empire's domain, but occasionally (some ways in to the simulation) they will go on raids of enemy territory to try to conquer their planets and stations. In my simulation, this is done by reducing the population of a planet/station to near zero. Stations are faster to capture, but also possess their own firepower. Reducing happiness is a byproduct of bombardment that vastly accelerates the process.
White are civilians. They travel between planets/stations, caring little about whose empire they belong to, and their arrival raises happiness. They represent ferries, luxury cruises, non-commercial traffic, etc. If happiness is too low on a planet, some members of the population may decide to take the next flight out and deposit themselves elsewhere. Occasionally during orbital bombardment of planets, you'll see a mass evacuation, where dozens of civilian ships flee, searching for new homes, more or less exactly as I described earlier in the thread.
You can hover over planets, stations, and asteroid fields with the mouse for more info. Unfortunately that is currently the extent of interaction.
tl;dr: Made a thing. Green miners, blue traders, red shooty guys, white civvies. Phones suck.