Sense of discovery and exploration, the interaction between different game mechanics, and the way the game teaches you how to do things while still making the puzzles feel gratifying to solve. Atmosphere is so strong. The visuals, sound, and art design all come together really well.
There's really a lot to like here. Whether or not it's worth the hype is a different question, but I'm very impressed at this game especially considering it's a 1 person dev team.