Kentucky Route Zero [0], which managed to not just be beautiful in its own right, but so perfectly captures the visual language it's aiming for that you'll just lose yourself in moments of experience.

Also, Pathologic 2 [1] (probably, if you have more fortitude than me, maybe the original or HD remaster are of value [2]).

All the best,

-HG

[0] https://www.gog.com/en/game/kentucky_route_zero

[1] https://www.gog.com/en/game/pathologic_2

[2] https://youtu.be/JsNm2YLrk30