Such a nice game :D
Please do not mind rest of the comment if you don`t want to.
Only thing I can think of not adding up is the personality-change at the end.
Its unrealistic, also there was no events adding up to it.
I have watched a lot of spooky stuff so If there were a couple more scenes between the Exit door and classroom ghosts scene, it would be great which showed Kat slowly turning that way.
Also, if this is no good then the end scene could be Kat not that badly shaken.
Plus, The classroom ghosts are shown full for whole 3 scenes.
It could be the first scene of ghost classroom with only eyes.
Second with eyes and hands
Third with nothing.
The nothing shows that Kat is already out of her mind and then the normal the Exit door end scene plays but instead of cruchy noice, it should be slash noise or boil noise since the bodies shown were slashed and the only other villain thing can be goo hence boil sound.
Plus if more horror or dementia component is good then show her successfully getting out through the door and going into her mother`s arms then only to find out she(Kat) is already dead and slashed.
If you read through this, thanks. Just giving opinion.
Very nice game by the way.