This is a very clever game and I absolutely loved it. I managed to beat it, with a bit of brute forcing in both puzzles to be fair. Some clues I didn't get (like the ship figurine in the second puzzle), but overall, this was very well made.
What I liked:
1. Beautiful aesthetics
2. Great use of audio and visual queues for feedback
3. The controls are tight and responsive
4. Challenging puzzles, but not too obscure to solve (you just need to be observant)
5. The notebook mechanic was a good addition to the game
What I didn't like:
1. I wish there was some background music playing while I was solving the puzzles. Each puzzle takes a good amount of time to solve and you will feel a bit frustrated during that time. A bit of calming music would be great in my opinion
2. The up and down arrows on the door combination keypad could have a different color or have a light on them so the player can immediately see them (took me a second to see them)
Other things and suggestions:
1. In the second level, there's a bug where you can pull the last piece of paper without needing to solve the square puzzle (idk what it's called lol). I solved the puzzle anyway, but I didn't know that it unlocked something I wasn't supposed to find before solving it
All in all, this is a great game, and I would love to see the concept expand into something larger. Great work :P