I don't think any game has filled me with dread quite like Subnautica. The way this game so easily taps into the fear of the unknown and very quickly turns that into straight up thalassophobia is incredible. For a setting that is almost entirely contained to the ocean, there is an amazing diversity of environments within and some of the coolest flora and fauna in any game. The game perfectly balances exploration, building, and survival, and it's one I want to keep revisiting, despite having beaten in multiple times!