Welcome to Cold Waters.
Cold Waters is spiritual successor for the old 80's Commodore 64 game called Red Storm Rising.
Released Jun 4th, 2017.
Cold Waters is quite arcade game, very easy to get into but still having somewhat requirement for nuclear submarine warfare. Cold Waters is no simulator, that's for sure.
PMC provides hassle free Downloads page with direct http links and 7zip files.
Looks like campaign starts with random mission, at least its different mission every time you start.