Just pulled the trigger on this game tonight, and played for two hours without noticing (long time for me). It's an exploration and survival game, pretty much underwater (thus the name). I can see why the Steam rating is overwhelmingly positive. Gives you a good sense of advancement and it's pretty intuitive on figuring stuff out for yourself. I suck, so I turned off food and water. Food was easy, but about the time I figured out what gave me water, those things disappeared and I couldn't find them any more.