I've not touched it in a long ass time, but I've got about 400 hours in HOI3 (not 4), maybe 50 in Darkest Hour too, which is how long it took me to accept properly that I didn't just need to give it time, I really just hate how it feels to move units and engage with the combat system in that game. Big fan of the retro feel in all the fonts, flags and animations in the latter game though.
But I do have this old screenshot in which I learned in very profound terms just how good building forts on islands can be.
