An RTS where you're not some omniscient being, but instead a general, sitting in your tent getting reports from the frontline. The map would be just that: a paper map on your table. The big thing? You don't need to stay in the tent. You could join your forces and fight side by side with them, issuing commands via radio without the help of the map, only the reports and what you see. Preferably, I would put this during WWII, and have a campaign. With no missions.

Being the general, you choose which route to take through enemy territory, and the enemy will counter you in order to defend themselves. Each battle's map would be generated based on a highly specific set of parameters, taking into account the specified terrain you are attacking into, where you are attacking from, and how well fortified the area is. Important places such as cities and sites of major engagements would have preset maps based on the historical battles that took place there (So you could go and defend Bastonge yourself, or relive the fall of Berlin). If you die? That's it. Game over. Obviously, you could retreat if you're losing, but that would give the enemy a chance to advance, and they won't just sit inside their borders while you ready yourself to go back. The game can just as easily become you desperately defending your home against the enemy.

This game would also be infuriatingly hard, with the AI being the best it could possibly be. Two difficulty levels would exist for people who don't want to spend their life trying to get through the tutorial, being an actual easy mode, and a mode where the AI knows about everything you do and counters it using the usual AI. Basically, a mode for wanting to roleplay a heroic sacrifice.

As I mentioned before, the setting would be WWII. As in, actual, no jetpacks WWII. Technology would stay the same as it did IRL, and there isn't some made up evil HydraDeathsheadsocietyOrganization that's trying to do "X EVIL THING", it's just actual WWII. Until you show up and intentionally lose the war against France as Germany for the lolz.