Either Slime Rancher or Subnautica.
Slime Rancher has no real ending, but it's an early access game on steam so it's a tad unfinished. It's fairly easy to collect higher value slimes to get the in-game currency easily if you know how. After that it's just completionist things like collecting Slime Keys, achievements, and popping
Gordos with copious amounts of food.
Again, Subnautica has no real ending but you can reach endgame within a few hours to a day or so. It's an open exploration game with a resource gathering element located underwater on a water planet. Fairly small map and quite easy to gather blueprints and the materials needed to survive. Again, game's early access so a lot of it is subject to change. I hope they make the resources renewable. Titanium is I think.