Hex-based, turn-based operational Napoleonic wargame with only a handful of scenarios that has options for extreme fog of war where the positions of both enemy and friendly units are by report only, they may have moved on since you last received a courier, the timing of which depends on their position relative to your headquarters.
At $8 right now, you’d probably be a fool not to pick it up! http://www.matrixgames.com/products/282/details/Campaigns.On.The.Danube
Was just updated a couple years ago, too. Runs perfectly fine on my Win7 desktop and mostly fine on my ultra high-rez Win10 laptop, just with a little oddity in the screen size, nothing major.
Pretty sure it does PBEM, and boy I’d sure play it against you if you wanted to slaughter somebody.