[Puke]

how about the ability to change your racial attributes and bonuses mid-game? Things like Eugenics projects and Genetic manipulation could help you build better people.

maybe the game could keep track of the different types of population (also handy for having alien races maintain their own bonuses while in your empire) so that planets with genetic manipulation facilities would be exporting population to worlds without them (sort of like organic replicant centers, but converting existing population instead of cloneing new)

there might be a chance of rioting if multiple population types share the same world, and there might be a chance of revolt if a planet is mostly populated by a population type that is not your primary. Thus, you breed a better type of your race, and they want to break away! so it would be important to make sure that all your population is changed quickly and at the same time, so that you dont have riots or rebellions.

maybe the game would also keep track of how many of your citizens you jetison into space, so there could be riots if you are organizing "purges" of the older inferior species.