Have you ever tried Valkyria Chronicles?
It's set on an alternate Earth during WWII, and you're in charge of a squad fighting off that world's equivalent of a German invasion. The game's combat mechanics are rather ingenious but still simple and straightforward. You get to know each member of your squad intimately, their strengths and weaknesses, and you're still pressed to use them in the best way possible given your tactics and the objective of each battle. It's a lovely combination of on-the-ground wargaming, rich story, and well-designed combat. ^.^