I want an invasion/colonization RTS of sorts, with a big overgame along with the regular fights. Say you and some other faction(s) are making planetfall. The planet isn't big or most of it is water or something. So you're all stuck at various parts of this big continent which is genned at the start. It is then divided into a bunch of sectors which would be your average, small or big RTS maps. You start off with an initial base and some units. You then probe off the surrounding sectors, looking for resources or other stuff (some premade things being placed around the continent would be cool too, like precursor tech or somesuch).
As you spread out and explore the native life and of course the other faction(s) will impede your progress and harass you (sometimes outright blocking you). So you need to find resources to build up your forces to push out further (either to just take the entire continent or to find something or just survive against increasingly harsh odds) while having to protect what you already took.
The kicker is that you can't go into this overworld mode a la Total War. You're always looking at the RTS mode and you switch between maps while also being able to order units or convoys from designated bases (which will then need to travel to the requested destination, which will take time depending on the mode and might be dangerous depending on the route). This way you need to plan ahead because if you get shafted and need reinforcements they might not make it in time, but you could amass them in a nearby territory and counterattack as they regroup, or even try and cut off their reinforcement convoy before they get to the fight, or just pull back to a fortified sector.
This way you fight for teritory and resources, both with the other faction as well as with whatever native life thinks you're not welcome. You tech up, and develop, growing your armies and power from a small expeditionary force that plays more like an RPG focused on exploration to this grander RTS with units and buildings and everything that comes with that. And of course your units and buildings require some sort of upkeep which forces you to spread out more and more to find richer resource spots (which could be located around the middle of the continent, which would also be more dangerous) so clashes would develop there late in the game, and heck you could easily lose a battle or two which then gets turned around because the enemy spread out too thin while pushing into your territory and you were able to take his undefended outposts.
So yeah, wall of text, probably poorly explained or thought out but I want to see this.