Everyone is just saying actually popular games, but ones they don’t think are popular enough. If people don’t have to look up the game, it’s probably not answering this question (with a few infamous exceptions maybe).

Mine would be Stationeers. There’s no real action or anything. It’s a game about designing, building, managing, and automating a station on another world. Each world has its own issues, be that Luna with a vacuum, Mars (the easiest) with storms, no breathable atmosphere, and cold, Venus with all the Venus issues, or some made up planets with crazy problems. It simulated gasses and liquids, replicating the refrigeration cycle so you can make your own heat pumps for cooling. It’s really cool, but complex and potentially boring for most people.

It’s made by the studio making Kitten Space Agency. It’s a studio created by the DayZ mod creator, and they seem really cool. They’re very much not profit motivated, and I think they’ve said developing Stationeers is costing them money, at least at one point, and KSA is planned to be free and donation supported.