I was having this issue where CK2 would just crash to the desktop as soon as I launched it from steam. I was able to fix it by rolling back to 2.0.4 (right click game > Properties > Betas > Select 2.0.4). Just thought I should post this here if anyone else runs into the issue and is wondering what to do, I have reported it on the Paradox forums (http://forum.paradoxplaza.com/forum/showthread.php?786840-LINUX-CK2-latest-patch-causes-game-to-crash). I think you will need an account and the game must be registered to the account for you to see the post. (ps. for those of you who were helping me in the EU4 thread, I am going to try this for EU4 and see if it works).