Zelda Breath of the wild for me. Don't get me wrong I enjoyed Tears of the Kingdom but breath of the wild scratched a perfect itch for me. Especially master mode. Well over 1000 hours played.

Super Hexagon

It's about as simple as a 'modern' game can be (I read there was even a port of it to Commodore 64.) but it's a finely tuned machine. When you lose - and you will, a lot - it feels like mostly your own fault and not the game's.

The difficulty levels very accurately start at Hard for the easiest one. There are 6 total levels, the next 5 difficulties are Harder, Hardest, Hardester, Hardestest, and Hardestestest.

With much time and luck I can beat the first level (unlocking the 4th). On a lost save I had unlocked the 5th level by completing the 2nd, and have only ever seen the 6th in videos from other people. I would have to beat the 3rd to see it myself, and that's not happening.

The criteria to beat a level is "last for 60 seconds".

Baldur's Gate 3 is a good game and a worthwhile experience but you can absolutely make quite a lot of very valid critiques about it.

Historically a masterpiece has been a (or the) work that demonstrates an artist is capable of utilizing their medium to its fullest extent, i.e. it has been mastered. Per ye olde Wiki:

Historically, a "masterpiece" was a work of a very high standard produced by an apprentice to obtain full membership, as a "master", of a guild or academy in various areas of the visual arts and crafts.

In that light, I'd say the best qualified would be games that completely utilized the capabilities of the platform they were designed for or, perhaps of interest to more people, expanded what everyone thought could be done with those systems. Games which were furthermore well polished and complete, and did not have much room for improvement taking into account the constraints they had to work with at the time. (For instance: No duh we could make Mario 64 run at a higher framerate and have better textures to look nicer on hardware now. That doesn't mean it wasn't arguably a masterpiece of its time, on the system it was on.) This doesn't just have to be technical stuff -- It could be the way the game used storytelling, its gameplay mechanics, or anything else.

Heres a list of some favorites:

Imperfect perfection: Morrowind

Perfect perfection: Starcraft Brood War

Objective perfection: Plants vs Zombies

Subjective perfection: Knights of the Old Republic

Perfect for its time: Gauntlet IV

Perfect timeless: Sonic 2

Perfect for its genre: LOZ Minish Cap

Perfect All-in-one: Shenmue II

Then Breath of the Wild and Tears of the Kingdom belong to that category - run smoothly as fuck on one of the lamest consoles there is, and are beautiful and complex.

Yeah for a third person isometric RPG with non-linear branching storylines and deep thoughtful story, Disco Elysium positively blows BG3 out of the water.

There hasnt been yet a game that could replicate the experience I ld had when I played Planescape: Torment

I also maintain that Breath of the Wild was superior to Tears of the Kingdom. Apparently this opinion makes Zelda fans incredibly salty.

For be it's still System Shock 2

Holy shit somehow no one has mentioned:

Nier Automata

It counts as a masterpiece because of how well it blends game design, gameplay and story. I have played very few games as thoughtful, or that weaved the gameplay together into the story it was telling in such a meaningful way. I never thought once in my life that I would think philosophically about bullet hell but somehow Nier Automata has something profound to say and even manages to say it using bullet hell as a gameplay mechanic.

On top of all this, it also has a lot to say about classical philosophers, their works, and honestly deeply subverts things they had to say. It asks tough questions about their thoughts and ideas, once again, through gameplay. Numerous characters are named for classical philosophers: Pascal, Jean-Paul, Simone, Engels, Immanuel... (Yoko Taro obviously has feelings about how Jean-Paul Sartre treated Simone de Beauvoir.)

Further, Yoko Taro is doing something that a lot of game developers fail to manage to do: He is embracing gaming as a storytelling medium and eschewing the traditional three-act arc from film. Because gaming is not film. As Marshall McLuhan posited, "the medium is the message" and unlike other developers Taro's writing is aimed at the medium he is working in instead of leaning on the ropes and tropes of other mediums. (Referring back to above, tying the gameplay into the story, focusing on the medium)

It's basically impossible to not break down into tears at the ending.

Don't write it off because of the scantily clad anime women. Stay for the depth of the human condition. It is truly a masterwork in multiple respects.