Tunic. I feel it is overhyped to the point people will think there's a huge Fez-like gameplay twist, but there's not.
It's just a really really good Zelda-like that uses an unreasonably charming illustrated manual to successfully spark the sense of wonder/discovery/mystery of playing games as a kid in the 90s.
And again I've really over sold it there. It's not even nostalgic - it just gates knowledge in a fun/creative way
Subserial Network. A weird little pseudo-indie game with an odd retro-futuristic vibe. It mixes cyberpunk post-humanism with web 1.0 nostalgia. You're part of an organization that deals with subversive synthetics, and your task is to locate a leader of this movement by infiltrating their online spaces. The game presents you with a handful of windows (email client, browser, lo-fi media player, etc.) and the gameplay mostly consists of reading to find clues to piece together and keywords to search.
I greatly enjoyed the vibe and world-building, and was pleasantly surprised by some of the reveals. The ending was a little abrupt for my tastes, but overall this has been one of my favorite gaming experiences this year.
I highly recommend it if you enjoy cyberpunk (the literary genre), early internet nostalgia, or epistolary storytelling.