Programming Languages Used by Paradox

[Nosferatu]

Hello everybody!
Maybe this question will be dumb but I am so curious to learn it. What programming languages are Paradox actually using while developing their games? Is it C++, C# or maybe plain C? Just to trying to understand which language should I start to learn and it it is even plausible and possible.

And especially I want to understand about Crusader Kings series. Which language was actually utilized for the first one?

 

[fnt]

I don't know how much changed in the last years, but i think this is still accurate: https://forum.paradoxplaza.com/forum/index.php?threads/programming-language-of-pdox-games.705797/

 

[Idicus]

According to the History of the Clausewitz Engine talk at PDXCon the Clausewitz engine is written in C++