the games on my list is a bit old if not just old but they are the most immersive/escapism games EVER!
i would like to list some NSFW games but even the good ones fall short counting at some point in all of them the story just falls off at some point.
the 1st Mass Effect game
Fallout 3
Fallout 4 (Fallout 3 has the better story but its shorter)
elder scrolls 3: morrowind
chrono trigger
I don't know, kinda hard to think about it, depends on the criteria. I got very into my playthrough of The Witcher 1, read all the scrolls and shit it had around, did all the quests I could find, took me a little while to get into it, chapter 1 is slow but near it's end and specially when you enter Temeria the game gets very good, I really liked the dialogs with NPCs at the time I've played (around the time Witcher 2 launched) in a way I just don't anymore, I can't bring myself to be engaged into a particular world the same way anymore. I did 100% of Witcher 3 but I don't feel that I got as hooked up as I did with the first one. Other great games that acomplished similar things for me are KOTOR 1 and Mass Effect Trilogy, RIP Bioware
If the criteria is all about playing not noticing time passes, probably some roguelike, dead cells, slay the spire, enter the gungeon, vampire survivors. It's all about wanting to go back into a run to not make the same mistake again. Breath of the Wild when it launched I could explore the shit out of all that open area for hours and not feel time passing. But I like the world immersion aspect more as it's something I think I can't feel anymore out of a videogame.
For me, it would have to be armored core, red dead redemption 2, and signalis. You can really get lost in the story. I won't lie, it hurt every time, but definitely worth it. If you feel pain after the story of a game no matter what ending, you know it was a good game.
I feel like Artemis had me the most engrossed. I just want to take Artemis and teach her how the world works. Especially every time she *coo'd* before she knew how to properly speak/emote. It was too adorable.
SFW: Hard to say. I get immersed easily, especially with narrative focused games like the newer God of War's and Spider-Man games, Disco Elysium, of, unfortunately to some extent, Honkai Star Rail. But also it's easy for me to just fall into a rhythm playing games like Minecraft or No Man's Sky while listening to audiobooks or watching tabletop actual plays and just grinding stuff to grind and enjoying the process.
NSFW: Degrees of Lewdity is easily the one I get most sunken into. I'll spend days playing it exclusively sometimes, and is one I've spent a lot of time with. On the narrative side of things, I once spent several hours reading lore entries for Re: Dreamer just because, all before ever hitting the first sex scene. Definitely not something most people can enjoy doing but sometimes I see world building and by brain goes brr
Edit: Got rid of an emoji because something decided I'd rather use some dumb smiling circle rather than type out the name of a visual novel that happens to have a : in it