Hey !
So I'm very sorry because I didn't have much time and couldn't read through everything. Those type of games are not the game I usualy play and enjoy but I still liked it ! I think that it's hard to create a good atmosphere in the time of a jam but I truly think you did a pretty good job especialy with the graphics and how they progress throughout your playthrough.
That being said I feel you could have a better atmosphere even if you had little time during the jam. I think those steps could have been down. I think the music is pretty repetitive and there are a lot of free music out there that can blend in the atmosphere a bit better. Also some sound effects would have been super nice. Something else than the classic unity footstep sound, something more soft would have been great. Maybe a grandfather's clock clicking or the wind in the room, some little stuff like that anchors you even more in that space.
I really think sound is important there because you'll spend a lot of time reading, and you don't want people to go crazy while they do, sound and music has to be dynamic and accompany you through this journey.
Anyway I loved the mirror like everyone else, awesome game mechanic.
Thank you for making this !