If the vanilla experience in Hearts of Iron 4 isn't doing it for you, a total conversion mod might do the trick. These are ...

So you looked at the long list of Paradox game converters, able to convert one single historical timeline of save games all the way through Attila: Total War, Crusader Kings 2, Europa Universalis IV, ...

Automatically converts mods to the latest version of the Cortex Command Community Project. This program presents a GUI for the Cortex Command Mod Converter Engine library that is doing the hard work ...