In the expansion pack, Alpha Centarui: Alien Crossfire there were 2 alien factions alongside the usual human factions.  If the aliens or humans took a base from the other, the base was reduced to 1 population, and the rest of the population took flight in colony pods.  This represented the two species being so radically different that there was no possible way at coexistence within a single base.

I would consider this the baseline, and then if we want to get creative with coexistence, hybrid cities, etc. we can hash that out.

If you edit the original post, you should be given access to a drop down menu of subforums to which to move it.

i like both idea's though thinking about it reminds me of age of wonders, where you had the choice to assimilate the population so you oculd replace it with your race, or try and make them like you before they rebeled and went neutral...

had some fun situations playing as halflings trying to make undead like me then having elves get pissy at me instead, though not sure that sort of thing would apply to elemental (need to play the game before i can have an opinion either way )

If any of the population of the different races city survive, it would be awesome to either see them as still part of the city, or become a wandering group a neutrals that may present themselves as a future danger to you, altohugh if they are marked as refugee's, would it do something negative towards your moral if you attacked them.