I got the EU3 itch and it refused to launch, would lock things up nicely tho for win10, had to 'sign out' so its force crash the game because it wouldnt let anything sit on top of it in the main panel area.
I had to do a combination of things
1)the d3dx9_41.dll file. Just google it up, its easy to find. Drop it in the game's base directory(folder) with the eu3game.exe
2)set eu3game.exe for compatibility mode WinXP SP3
3)run as admin
4)disable fullscreen optimization(this one threw me for a bit. I could get it to load in windowed but not fullscreen then I happened to look at the compatibility tab again, saw this and tried it for lack of other ideas.

This done it works just fine now and launches via steam properly as well, but no steam overlay.