BlackerICE is an extreme overhaul mod for the classic Hearts of Iron III game from Paradox Interactive (both visually as well as game content). It was originally based on the popular BlackICE mod for HOI3, and was founded and is maintained by Marneman, one of the original BlackICE developers. Yes, I tried HOI4, and I don't like it. Paradox has removed some of the key features that made HOI3 such a fun experience. Sorry, but I don't want to play a supply sergeant simulation. :) If you are like me, and think HOI3 is a better game than HOI4, then I invite you to come check out BlackerICE!
The USA now unlocks historical National Guard and Reserve units on the dates they were historically activated for service. They start with National Guard garrisons and will eventually upgrade to full divisions (though they will need to reinforce from the manpower pool once loaded, of course). Each has the historical unit counters as well. Here's a little preview - there's a ton more.