For pure amount of enjoyable play hours: Skyrim, hands down.

For emotional/philosophical impact: Either Journey or SOMA. Both had a big impact mentally for me.

The Journeyman Project 3 - A legacy of time. I got it as a gift when I was a kid it was only in English and I didn’t speak the language yet. That game was my tally on my language learning skills. I also have a love for point n click games (Myst, Atlantis, Amerzona, Versailles and all of Cryo games)

Noita

The Witness

All the story based games:
TT The Walking Dead most, but Firewatch and Life is Strange in a close second/third. So many feels I wish I could relive.

gives me nostalgia

Definitely Xenogears on the PS2. I loved that story

Dark Souls 1

Part 2, 3 and not even elden ring did manage to reach the same athmosphere and i mainly atribute it to leveldesign: Dark souls 1 is an apocalypse brought about the fact that every last being is slowly but surely driven insane before losing any semplence of self altogether and bekome huskless zombies. And the world is reflecting this: It's like a surealist painting. When you zoom in very far everything makes sense, ther is a wall and a medieval city and beneath is some sewers, but when you zoom out the city is actually in front of the wall, but then you are on top of the wall which is kinda acting like an entrance the the next area and not like a wall at all. In the other directen you go down the sewer, but then drop into a hole to be on top of a wall again with another city beneath you. And you can go even further down, either to a hell like environment to yet another city even lower, or throug a giant dead tree to come out on a beach with a clody sky above which absolutly does not make any topological sense at all. And yet this map is intricatly interconnected with several passages and elevators. Not from me: It's like with the first flame fading it's not the dead rising, but time and space itself is collapsing, that's why you can't die, that's why other players can be summoned to your world, and that's why the whole world, while still being connected, makes no sense at all.

Also 2nd choice: Obligatory: "Spec Ops: The Line"

If you haven't played it yet: Do it without reading any Spoilers.

Ark Survival Evolved.

Peak Ark is when you have no idea what you are doing and keep being shitmixed by velocipators. Huddled in a darkened shack with the outside chewing it's way inside while you scream in terror.

Then you finally get a bit of a handle on what is going on, tame your own raptor and BAM giant snake knocks you out and as you swim back to consciousness a giant croc grabs you in its mouth and launches into the stratosphere.

Later on it's all iron man suits and minmaxing every fucking thing.