Oh, this one's easy: Subnautica.

Horizon zero dawn.

Mass Effect Trilogy

Halo CE, but in 2001 when it released. I remember how incredible landing on Halo felt. Also the flood reveal.

TUNIC. It's impossible to truly explain without spilling anything. But I don't think any other game could do what that game did again and succeed, unless of course whoever is playing it hasn't already played TUNIC.

Myst on the PC

That shit broke my mind as a kid. It was life changing.

Fire watch and portal.

Chrono Trigger.

Because Chrono Trigger.

Maybe FF8.

Also because Chrono Trigger.

Portal 2

Any of the souls games. The exploration in those games is so damn good.

Shadow of the Colossus

I mean, it's the Outer Wilds. That's the right answer to this question.

But also, Hellblade was absolutely incredible to play in one sitting with good headphones in a pitch black room. It took a few minutes to get used to the voices, but once I was finished with the game, my mind felt strangely empty for a while

Read Dead Redemption 2. While I didn't like the Intro as much, it really made for quite a journey.

Portal and Portal2. Epic games that just aren't quite the same on replay

In no particular order:

Undertale, Chrono Trigger, Donkey Kong Country 2, Final Fantasy III/VI, Slay the Princess. All those games "lose" something the more that you've played them.

Fallout 4, it's taken me ages, but I finally have a console mod set that makes survival mode what I always wanted it be, and being able to explore the world that way with fresh eyes would be amazing.

Mario 64 for that holy shit this is the future of video games moment

Stardew Valley...

It's World of Warcraft, and it includes being the age I was with the knowledge I had at the time. Vanilla was such a stabbing in the dark experience, and then stepping through to Hellfire Peninsula, what a vast view compared to the prior landscapes. I miss not knowing who's "bad" and who's "good" and who's "meta"

Maybe that was always there (though I doubt it was there as much without all the third party metric collecting interference) but that's why I caveat with knowing what I knew at the time

Man I just finished the DLC for Outer Wilds, then I went through the main game's ending again. And holy shit if it were possible for a game to make me cry, then that ending would do it.

Planescape: Torment

I've asked my partner... in case I ever get Alzheimer's... to just plug me in front of that game forever.

Yakuza 0

Both portal games

Dark souls

STALKER SoC

The half life games

I'm definitely showing my age here, but for me it would be a PC game from 1996 called The Neverhood. When I played it at age 15 a lot of the biblical overtones were kind of lost on me, and the guy who created it turned out to be kind of a nut job, but it's one of the most fun and creative puzzle games I've ever played. The entire game was made in stop motion with real clay sets and figures. The music is amazing and the soundtrack is definitely worth listening to on its own even if you don't play the game. I've replayed it on emulators a few times over the years, but it was nothing like experiencing it for the first time and discovering all the puzzles and secrets! This was pre YouTube so even if you had to occasionally check the walkthrough you still didn't really know what to expect next!

Golden Sun and Gothic 2

Definitely Littlebigplanet 2. Also, Skyrim.

Star Control 2

The Witness is truly amazing to play blind for the first time.

starcraft, warcraft 2, warcraft 3, world of warcraft (up to lich king) descent 2, descent 3, halo CE, the original dayZ (the arma II mod), unreal tournament 2004 multiplayer maps, life is strange

Conker's Bad Fur Day.

Although, really, it was a product of its time - not to mention the endless subtle (and not so subtle) movie references.

Also, classic LucasArts adventure games. Recently played through Grim Fandango for the first time, that was good, but it was nothing like Monkey Island and Loom.

Dayz.

There is no other game that has ever given me the same adrenaline rush as Dayz. It just hits different. The learning curve is a bit steep, but every step and every player encounter is a memory to remember. Really wish I was less experienced and not knowing the maps inside out, really wanting to get lost again not knowing might what happen next.

The game has come really far and more players are playing it now than ever. The game has great modding support and community servers. If you have never experienced Dayz then you really should give it a try as it is often on sale.

But remember: no mic, no life.

Spec Ops:The Line

All I wanted and expected was yet another mediocre military schooter. Mechanically I got that. What I not expected: how hard the story would hit. I am so very glad I went in blind.

Full Throttle.

Kick ass soundtrack Main character has good quips (I'm not putting my lips on that) Good old SCUMM interface Crazy motorcycles Comedy, drama, and most importantly motorcycle fights on desert roads.

RDR2

Breath of the Wild

Assuming it was also back in the relevant time, and not just the current day with memories wiped - the entirety of GTA 3, Vice City and San Andreas.

FFVII, FO3, Homeworld 2 are the three that immediately spring to mind