I would like a rather simple real-time war-game, as played from the POV of a field commander. You don't have a real-time view of the battle; all you have is signals, which are rather stylised, and a 2D map, with unit symbols on it. The map is always a bit out-of-date, except when a signal has just been received from a unit. Think something like a battalion HQ tent, with staff.

Commands are also stylised; I'm not a military person, and I don't know how to compose field orders, so there would need to be some kind of UI that allows you to construct orders visually. But in the end, the order that you send consists of text. You can't order-around squads; you can only issue orders to subordinate commanders.

You also receive orders from above. You start with a mission briefing, with objectives. But your orders can be updated mid-mission.

So this would be essentially not a video game; there's no motion video. It's a text game, with a graphical map. For added entertainment, you could have a retrospective video playback; but you wouldn't have realtime video from the frontline that you could act on.

I once had a game a bit like this; it was for military use, and I didn't really understand the format of the orders. Also, commands were issued by dragging on the map, rather than by text.

Something like: "You will advance to grid square X. You are to avoid engagement. You will report enemy positions."

I'm thinking of modern warfare, with radios/telegraphs, air power and integrated air defence, armour, and intelligence staff. But you could maybe take it back as far as the Napoleonic wars, with dispatch riders instead of telegraphs.