So… how will colonies be handled? In spore it was just you have the colony until it’s taken over by blue or you win civ stage.
We could also have it where there is colonial “impatience” (IDK what else to call it but yeah) which acts like world tension like in HOI4 but only mother nation to colony. It starts off very low but as time goes on, the colonies size increases, and what the player does, the impatience can get higher. At a certain point, the colony will make a series of demands that get bigger and bigger that if you refuse, they can declare independence, and war will go on. Also, if your colonies are below 50% impatience and 1 colony has successfully rebelled, they can get a peaceful independence if they ally with the mother nation. Also, successful attempts at rebellion will increase other nations impatience, and failed rebellions will lower them.
Pre-Colonial tribes. How could the colonial superpowers interact with them, and what if the tribes were very advanced? I think first trade goes on and as colonies grow the colonial nation can send expeditions to raid and kill the tribes, to get more land. If the tribes were advanced, I think colonization for other nations (other than the one who made contact and was severely annihilated, unless that one was behind) is a no go, and if they make contact, the tribes could even attack the colonial mainland.
Also, what if you want to play from the perspective of the rebellion? Well, I don’t think some people would want to do that, and some people do, so if there is a button that appears when the rebellion comes that could say, “Do you want to switch to the rebels?” and there could be a yes or no. If you play as the rebels, you are outnumbered, but you have an advantage. You know the land like the back of your hand and you know where the mother colonies troops are stationed. You would get (50% of X)% of the troops in the colonial nation where X = colonial impatience. So, if you have 50k troops in the colony and the colonial impatience is 80% then you would get 40% of 50k, or 20k troops. The mother nation will still have troops from other colonies and the mainland, so it still will be hard.
Good examples of the rebel colony eclipsing the mother nation are the USA and Brazil (at least after getting independence).
Either way works, maybe in the settings there could be a difficulty slider where you could change the complexity of the game, right next to the LAWK toggle.