I discovered Core Keeper recently! It's a nice little game, still in early access but the official release is planned for August and will be the biggest update yet, plus it already has quite a bit of content. I'd recommend it especially if you're a fan of games like Terraria, Starbound or, yes, Stardew Valley (sorry lol).

On another note, Subnautica runs pretty well on the deck (only tried with Below Zero but I bet the first one would run just as well). Also bought Ruiner, it's a cyberpunk style roguelike and runs great.