Subnautica is an open world exploration and adventure game that's all about trying to uncover the secrets locked away within the depths of an alien world. And if that isn't enough of a reason to throw caution to the wind and dive alongside space-sharks, you'll be glad to hear that the recent Precursor update has added ancient artifacts and strange alien gateways to further spice up the gameplay.
If you're interested in seeing what these things look like, here's the recently posted preview trailer. And don't worry, the spoilers are pretty minimal given that the developers were wise enough to not show what lies on the other side. Have a look:
Besides all of the new alien relics, the Precursor update has also brought with it improvements to "The Lost River" and "Floating Island" biomes, the introduction of fall damage, the ability to use your PDA while driving vehicles, as well as a variety of other, minor changes. If you're interested in all of the details, head on over to the official website.
And if you're wondering whether Subnautica is worth your time and money, I would say the answer is a definitive yes IF you're into these sort of games. I've only played it for a short while, mostly because I'm not a fan of completing games while they're in a beta state, but the stuff I've seen so far was certainly gripping enough to tempt me into playing more of it. So if survival and exploration is your thing, you might want to give Subnautica a look.