Although War Thunder has been around for more than 5 years, today its players can enjoy the experience of a sub commander for the first time. Although the "Silent Thunder" game mode is now only an April Fool's Day joke, it might also become a part of the game in the future, as it happened with last year's modern tanks.
https://www.notebookcheck.net/April-Fool-s-Day-Gaijin-Entertainment-testing-Silent-Thunder.293686.0.html
It's a fun game and pretty interesting, I'm sure they will add more to it after beta testing, but its great. ;)