My absolutely most favorite single player and gaming experiences in general are:

1. Outer Wilds
2. Tunic

Their replayability is 0 but man do these experiences stay with you. I still think about outer wilds daily and i finished it last year.

Also a word of caution:
Both these games function with knowledge-based progression, so almost everything you look up about these games can be considered a spoiler and will lessen your experience with them!