Astroneer is a sci-fi sandbox game developed by System Era. You're a pioneer in a galactic gold rush. You can do a lot of stuff in this game but as of now it's just a sandbox. The soundtrack is very calming.
Astroneer has a dynamic inventory system that's fun to arrange and use instead of it simply being a magic backpack that fits anything like in most other games.
You can build bases and not even the sky is the limit as you can manipulate terrain and could build a mountain jutting into space with enough terraforming.
You can also build enormous limitless trains and haul just about anything on them which is pretty fun.