First of all, I really did enjoy this game and this entire series. I love your ideas, and you're one of my favourite game makers on Newgrounds.
However, I really liked the second game and had been anticipating the release of this game for almost a year, but I found it to be slightly disappointing compared to the ingenious second "deeper sleep". The reason why I loved the first two games is the deep link to human mentality you made, and that is exactly how each good game or movie succeeds; by giving the player/watcher a genuine emotional experience.
But since your art style is done using many pixels, these games always thrived on the suspense they created, making the player anticipate the next jumpscare, and not the actual ghostly scares or good graphics. What this final part does is that it killed the suspense by showing the monsters early and throughout the game. The ending is also rather disappointing, as it is a rather zealous attempt to include animation. I would say many games and movies make this mistake in the later parts in an attempt to thrill and please the audience, but ultimately this always fails because it was never the good graphics or monsters that they came for. They came for the puzzles and suspense and mental link. A guy getting killed isn't scary, a guy who might be killed any minute by a flying knife is. Finally, I found the repetitive music in the book room rather annoying, and the puzzles too easy and straightforward compared to the last two games. Not being able to return to the rooms with the buzzing bugs isn't very logical to me, and makes the game too easy, while in the last two you were continuously allowed to explore most of the map to find the answers to the puzzles.
That said, I meant no offence at all, I still really enjoyed this game and think your hard work paid off. I hope to play more excellent games from you, keep up the good work!
P.S. The hanged clown was my favourite part. It links back to the second game and is truly creepy, with a backstory that needed not be explained at all for the audience to understand what happened. This kind of stuff is brilliant!