Barotrauma
There's a game called Barotrauma. It's a 2D online multiplayer submarine game where you have to complete different missions. The game has many different roles such as captain, mechanic and engineer. All the roles have different tasks. There are also big alien creatures in the water which can damage you vessel and make water flood inside the submarine. The game is alot of fun, especially if you play it with friends.
The game is in early alpha stages and is free to download from the creators website. Barotrauma has also been greenlit on steam.
http://undertowgames.com/barotrauma/
-GarryTheGuy