Since so many people have already mentioned Stardew Valley, I’ll go for some lesser-known ones:

• Zero Ranger (this links to the demo): no joke, probably one of the best shoot 'em ups (or shmups) I’ve ever played. Sure, there are more challenging ones like DoDonPachi but in terms of visuals, sound, and even story I don’t think there’s anything that tops it. It’s also really weird at times but it’s so, so engrossing.
• Death Trash (also has a demo inside): a 2D action RPG set in a post-apocalyptic world full of eldritch horrors. It starts like Fallout but it gets weird fast. The visuals and the overall sound are purposefully harsh and unsettling, the difficulty is…not easy. But if you like something a bit different from the norm, it’s, again, pretty engrossing and think you’ll love it.