Antichamber for a good old school mind bending puzzle game
So many good ones in this list, cultist simulator will make you see the world through its game system afterwards, ghost of a tale is Soo damn cute and well done. Expanding on 5d chess I'd recommend 4D toys, a sandbox that will open your mind to the 4th dimension
The Level Design Book, an amazing free online resource.
The Level Design Book gathers level design knowledge for 3D video games in an approachable, up-to-date, and critical way. It is for designers of all experience levels and game engines.
This resource definitely deserves more attention, and, albeit being incomplete in some points, I've been finding to be extremely useful while designing my game, not just its levels. In particular the initial chapters about experience goals have changed my perspective on design.
I rewatched for the third time what we do in the shadows (2014), I love the quirky humor and the mockumentary type of filming