Knytt Underground comes to mind, It was a ps+ freebie, didn't know anything about it, loved it. Music, art style, exploration all great.
Cavernous wastes for PSVR wins though. It looks like a bad Descent clone with rogue like gameplay I normally despise. It was very addictive, great retro music, amazing atmosphere and quite challenging gameplay.
Closure is a puzzle game that I did not expect much of yet ended up enjoying from start to finish. Same with Antichamber and Fract OSC, amazing games.
I tried ETS2 out of curiosity and ended up playing it a lot. Really getting into it by switching the radio stations to the actual country I was driving through. Early morning German traffic reports or Italian night time radio for the added immersion factor. The only thing missing was the radio going out through tunnels :)