Before HOI 4 I always enjoyed the idea of being a 1940’s warmonger in the previous Hearts of Iron. A deep, compelling and engrossing World War 2 Grand Strategy game with a seeming less amount of possibilities to understand the grand scale of a war I’ve been studying for years. Somehow, I never got into it, maybe it was too complex, maybe I never understood the concept, maybe both.
Hearts of Iron 4 was a welcome change of pace, but it also came to me in a point of my life where I could spend some time playing it and understanding it. I was on medical leave due to a knee injury and waiting for transfer due to my recent promotion. The new HOI focus on productions, supply and war manoeuvres was just my thing. It soon stood out the idea that this new iteration was barely anything more than an engine shell of endless possibilities for grand-scale warfare.
By focusing on those three aspects and nailing them down precisely, it allowed modding to surge upon that very foundation. Want World War 1? Sure thing, bro. Keep those 3 basic ideas and change everything else. Change the focus trees, change the unit’s stats, change the 3D models, change the layout of resources and map, change what you wish, but if you keep those 3 pillars, the basis for a strong foundation is there.
Want a scenario about today’s events? Man, you got it! Change everything from WW1 to modern era looks and stats and there you go once again. Instead of outputting Mauser Rifles and biplanes you’re now forging M16 and B-1 Bombers. This is the main reason nearly every well-developed mod in Hearts of Iron 4 feels and plays great, because only rarely you find a disconnect between the mechanics and the theme.
The great thing with Hearts of Iron IV is that the foundation of gameplay will always be the same, and you can then build complexity on top of it. Its mechanical structure works great towards any kind of grand-scale thematic context: Hearts of Iron 4 is a sandbox and gives you a really solid box where you can add as much sand as you wish.

The following mods are advised:
-Millennium Dawn: Modern Day Mod
-Kaiserreich
-The Road to 56
-Hearts of Iron IV: The Great War
-Old World Blues