[PC] Realm.exe always missing

So I can't launch the game anymore, because the 'Realm.exe' is missing and can't be downloaded by Steam.

​

I already tried to repair the game through Steam, but it will either not find any problems or keep downloading a single file that always fails to download..

​

Even a full re-Install didn't help. I'm using a Microsoft Surface Book with Windows 10 if that helps.