I have decided to put here a few suggestions for mechanics that could be included in GalCiv III by expansions or DLCs. There are two things that I think that would greatly improve the depth, roleplaying and immersion of the game. These would be to see which race populate a specific planet (and if there is more than one race living there) and the ability to choose how to treat those people. Let's do the first idea first.

In Stardrive 2, each planet can be populated by more than one race, and this isn't limited to having a little list showing which races live on it. You can see the comparison between the number of individuals from each race through icons with an image of their respective race. Although these icons are used to direct the population towards food, manufacturing or science, they do a great job of illustrating the people who live on the planet. For example, let's say there are 10 billion people living there. 2 billions are human and the other 8 billion are aliens. This way, there will be 2 icons with the image of an human on it and other 8 icons with an alien image. I could also take humans from another planet and send them here, so to increase the human population.

Now, I propose that the same be done in Galactic Civilizations III, but using percentages rather than icons, so that it isn't to similar to Stardrive 2. This would enable the following scenarios: I'm the Drengin and I conquer the Altarian homeworld, Altaria. Unsurprisingly, I look at the population percentage and it shows that 100% of population is Altarian. But the planet is mine now, I do whatever I want with it, and the first thing I do is to send Drengin immigrants there. This way, the Altarian population percentage will slowly start to go down and a new Drengin percentage will show up and start to rise. In the first turns of immigration, the Drengins represent about 5% Altaria's population. Their number will then start to grow, and if I want them to replace the Altarian people there, I might want to enact some policies, such as mass castration or perhaps even genocide of the Altarians   Or you can just keep them as slaves. And this leads to my second suggestion...

Which is the ability to choose how to treat my own people and other alien populations I might have conquered. I could establish authoritarian governments or more tolerant ones by using the imperial management screen, or I could do it individually for each of my planets. If I take a new alien world, I could establish a harsh and opressive government upon the aliens, or a tolerant one to gain their favor and approval. And if I send my own immigrants there, I could give special rights or privileges to these immigrants, at the expense of the rest of the alien population. And obviously, all of this would impact on my ideologies. Also, having two or more races living together on the same planet would cause a lot of racial conflict, as you would basically be creating getthos.

I also had some other ideas, such as replacing the current food system, which control how much population you can have, for a system where your population will simply grow anyways, and farms exist to keep the people fed. This way, food trading between your colonies would be very important, and sieges could starve a colony. But as this would mean a change of the game design, I think it would be better to keep it the way it is.