This was honestly a great game! I loved the art style and also the whole creepiness of the game. The story was pretty great too! How the sister's demise was eluded to from the start; with the mails and everything. It was well done!
Only thing i can suggest is to add some background noises to creep out the player. And also have things being done in the face camera; like when File says that he snuck in through the curtains, maybe add a figure moving in the background or a curtain moving and same thing when he mentions the bookcase.
Also thought that the panel on the wall was completely random? There was nothing that eluded or made the player go to find it unless they were randomly clicking. (Or I might have missed something, sorry if I did.)
Other than that, the hidden messages in Morse and Binary were really good and added a layer of immersion, which was really cool! Nice job on that! Overall it was super fun to play and the platforming was simple yet challenging!