I'd love to see the ability to actually have multiple populations on a single planet: Such as the invader and the invadee, so to speak. So for instance, let's say you conquer a planet and they surrender with 25% of their population remaining. Fold that into the total population of the planet.
I don't think adding a layer of sub-populations would be a good idea. Add to fun, maybe... add to complexity, yes. The gameplay of Gal Civ has largely been on abstraction and not the details. Try to hard to force the details into the game and you begin to write another TBS altogether. I have no problem believing my population consists of a variety of intellectual beings / slaves of other cultures. But I don't think I need to know that 40% of this planet is Torian, because how does this play in the role of space emperor?
Will I have edicts to remove this populous?
Will I be able to expand this particular populous through inter species genetic manipulation?
Will I have to manage the unrest of the Torians when I'm at war with their friends?
What happens when my selected race becomes a severe minority in the population, will I lose control of my space empire due to the lack of support of the people?
If we do add these controls, won't this begin to dominate what I have to do in the game as I get 20-40 planets? Not to mention the 100's of planets of the enemy.
We have to recall that Brad has suggested that he would like to see 100 major civilizations on a map. Does that mean my population on a planet could be divided into 100+ different species to represent each population? Then it is feasible to have a planet where there is 10 billion people, and each race is represented as .1 billion. Or do we also include the minor sub-races that will be in the game, I could forsee another 200 of these individuals. Leave a population dynamic of 300 sub-divisions.
I like the idea, but it doesn't scale well with the game. Not tedious in the beginning, but in the end it is too much to worry about.
The simple control of picking what to do with the populous after combat may also get annoying, but I think it is better than nothing. I would rather see a diplomatic option for War. Go to war yes, but you can also threaten them further... (Choose how you will fight this war. Give a response to the enemy, in other words you select the option at the beginning of the war and you can't change it, until your war status changes with that civilization)
Surrender to me or I will exterminate the rest of your species." Leaving you no option when you invade, but you eradicate the population each and every time. (No war unrest penalty when settling a new planet)
For the benevolent action, "I only fight you because you make me. I will not visit any more cruelty to your species than necessary. Please consider peace." Always set the citizens free. (Population bonus on each conquered world)
For the pragmatic action, "Let loose the dogs of war. I shall reap what you have sewn." Enslave the citizenry when invading. (Production / Research / Wealth bonus on the conquered world for 10 turns). Production... slave labor. Research... species experiments, you have a lot more "willing" applicants. Wealth... Taxes on the sales of new household automated tools.