Neither of these are popular enough to be on the scale of LoTR, but in terms of atmosphere and detail:
Hollow Knight - my absolute favorite thing about it is each NPC has its own voiced language recorded, babbling in the background as you read the dialogue.
Subnautica (the first one) - shitting myself with each new experience is something I’ll always cherish. Highly recommend just playing without looking into the gameplay or plot. Has elements of exploring, resource gathering, base building, psychological horror (not graphic, just tense scenarios), sneaking.
I try to name unconnected things until I’m interrupted by a different thought, then when I realize I’ve gone off I play the unconnected naming game again. Doesn’t matter if there is a connection. Apparently this disorganized thinking is similar to sleep thoughts and can help get your brain in the mood for sleeping.
Example: sheep, glass, shelf, sock, alien, whisker, etc