Portal 1

Portal 2

The most recent is Stray. I loved the worldbuilding and well, the cat.

Half life 1 and portal 1

What Remains of Edith Finch. I ended up in tears after playing it. So beautiful.

Also on Android Monument Valley and its sequel. Mesmerizing games.

I also completed bioshock infinite in one sitting with my brother when I was younger. That shits a core memory for me now lol

Spec Ops: The Line. I started playing it in the morning, the story kept me engaged (and the gameplay was fun enough). I played it all day to its conclusion.

super metroid and metroid zero mission. Man I love those games.

antichamber literally kept me up all night until I finished it at 9am

Return of the obra dinn. Both because it's good and because I was worried my train of thought would be interrupted if I took a break. Took me ~9 hours and gave me a really bad headache afterwards, no regrets.

Inside!

Civilization III. I mean try to do it in one sitting.

I didn't do the whole game in one sitting but I was glued to my chair for hours when I started Deus Ex: Mankind Divided. Remember looking at them time on my phone and going, "huh, it's after midnight". Then again later and finding out it was the beginning of daylight savings time. Went to sleep, woke back up, and played all day again. Fantastic game.

Carrion. I was surprised how much fun it was. There's some nice but not overly difficult puzzles and some frantic bursts of combat

Devil May Cry, in an evening. Great experience.

Not quite one sitting but very quickly: Ori and the Blind Forest, Maneater

The Last of Us, Cyberpunk

Sleeping Dogs pulled me in real hard. I‘m super salty there‘s no Sleeping Dogs 2, I loved everything about this game.

If any of you like GTA style gameplay, Sleeping Dogs is that plus kung fu movie flair (even has a cheesy king fu story DLC).

Nioh, Nioh 2, Code Vein, Dark Souls 2 (I know), Fairy Fencer F, and Ni no Kuni 2 also put me in chains. Crusader Kings III has no real story but it made so many evenings disappear that I try to legit stay away from it lol

steamworld dig, started playing one morning and before i knew it it was evening and i was done lol

Oh my gosh, I played Black Mesa before the endgame released, you are a scholar sir

God of War on Ps2. I remember starting in the morning and finishing when it was dark outside. In fact I think I skipped eating and not even using the bathroom. I remember rushing to the toilet after beating it since my bladder was about to burst hahaha

The standout example of this for me would be Qube. I was having a bit of a difficult time when I first bought the game and that soundtrack lured me in and getting through to the end just became a total compulsion. I was a lot calmer by the time it was over, too.

Kairo had a bit of a similar effect on me, except that the very last jump in the whole game just would not work, spoiling the zen. Quantum Conundrum also got a full playthrough in one sitting but tbh I think that was because I wasn't enthusiastic about coming back to it another day.

Surprisingly, The Witcher 2!
I believe 3 and its DLC had come out at that point, meanwhile, i had paused the first, which I had bought on release, somewhere before its third act. Somehow I got back into it and finished it in a few weeks.
Then I booted up the second opus and the changes were so drastic! It was amazing! Everything that was a hassle in the first was pretty much gone!
And that story was fantastic, with a proper dilemma at the heart of it : you had to pick a size and stick with the consequences.
I finished the entire thing in a very long weekend, completely enthralled and picked up the third instantly afterwards.
And somehow things got even better!

Little Nightmares, What Remains of Edith Finch.

Baldur's Gate: Dark Alliance. Granted I had a lot less responsibilities back then but I thoroughly enjoyed the game.

Primordia.
The Excavation Of Hob’s Barrow.
System Shock (1994).

Inmost - short platformer/metroidvania game with a brutally emotional storyline.

Far: Lone Sail - short puzzle/platformer game. Chill as fuck, great atmosphere and music. Story is only really gleamed from the environment that you traverse.

Cataclysm Dark Days Ahead. Because I usually die in like the first week in game lol

Stray.

I wanna say Yoshis Island for SNES but it was so long ago I don't remember if it was one or two sittings. Dunno about the "that was so good" part though. Just completed it :)

Max Payne!

Plants Vs. Zombies!

My wife and I just sat there like... zombies... for the whole day and night until we finished it, and then went to bed surprised and happy when we got our musical reward at the end!

The Flash gaming era at it's best.