I thought that the pop display meant all "able bodied, ready to be used" population. Not ACTUAL (civi) population. Think of it as people in military or civil service. They can be put to any use, and will be if the situation arises. I think the max pop is 100m. For reference, Earth has 6b, and growing. I'm not argueing that 100m is enough or too much, but that number, to me, clearly represents the military/civil/elite/trained population that can be used for government service at will.
That IS ACTUAL civil population. Because its not millions its
billions. Look closely. And then think again about Earth 6b reference.
I belive planet takeover system in GalCiv is pretty much idiotic. And thats very strange, because rest of the game elements are awesome.
Because:
a) We can put billions of our taxable population (which includes everyone from artist to mall's clerk) to war. To one ship..

Planet that was attacked as well has billions of people who wants to die rather than pay taxes to other emperor.. neat. So all of them leave their cities and gather in one place so whole thing can be done quick. (one week war) Based of course not, of how you good at lasers or missiles + troops skill BUT on random numbers + troops skill.
Honestly, how many of you ppl, saved your game before planet invation in order to insantly try again if it fails. How many did the same for space fight ?
I think much less, because in space techlogy takes place instead of random numbers, and outcome won't differ much.
Now I wonder. What is the reason that ppl at stardock didnt make planet fight similar to space. Just create one more tech to study, lets say "Ground units hulls" and create tanks/etc to fight for planets using same three attack/defence techs ?