Be careful with Subnautica. I lost 75 hours of my life in the blink of an eye to that game. It's easily one of the best survival horror adventure games ever made.
Terraria is also up there. Once you play it you never really need to try another side scrolling 2D Minecraft like game again.
I'm about to finish F:NV soon. Took me a while and was a great experience so far. Except for Old World Blues DLC which I really disliked and Honest Hearts (the Zion one) which kept crashing constantly for me so I had to skip it. Otherwise really good and really better than bethesdas F3, true to what everyone said.
I got NV modded up through the Viva New Vegas guide, so hopefully that fixes the crashes for me. Figuring out how to mod it on linux was surprisingly easy too, thanks to the MO2 linux installer on github.