I just played this and it was pretty great! I loved:

1. The atmosphere
2. Your overall narrative was super strong
3. The voiceovers! 
4. Your OST was also great!

Here are a couple of notes I made during my playthrough:

• Making the dialog so long and unskippable affects pacing pretty heavily - it was super interesting, but I'd say to maybe have the player be able to drop the note to keep exploring while the voiceover continues. That way players can take in the full lore while actively exploring/experiencing the environment!
• I did soft lock myself when using the stairs by falling off to explore the area below. I wasn't able to jump back up and wound up restarting the game to finish it.
• I wound up missing the last note because level progression was tied to the keys in my second playthrough - maybe you could make the notes fulfill the same function as the keys, or spread them out more throughout the level to make sure player get to notes prior to keys.

Overall, this was great! I really hope to see a full release in the future!!!