That was a really nice game.
A few comments, technical and on content, including spoilers:
1) Make sure players understand that they can drag around the room to see more of it. This was not obvious to me at first.
2) Looking at the playthrough of navarsai, he was "stumped" by the origami/password/safe puzzle for some time, because he did not remember that multiplication is supposed to go before addition. It's always frustrating to see someone "get" the puzzle and then be stopped by a simple technicality. If you arrange the operation symbols in the order " * * + " instead of the current " + * * ", you will avoid this problem.
3) This password puzzle seems to be randomized, as I got a different color order on the tv and therefore a different password. "The Internet" (according to some discussions I have read) seems to hate this, as it interferes with their ability to use a walkthrough. See Monkey Kombat explanation for a historical example that I still remember (I liked Monkey Kombat, but was apparently the only person to do so).
4) As an addition to 1), as I watched navarsai's playthrough to find the one collectable I missed, I found it to be the "Alex" on the lion origami. I had no idea that you could interact with objects directly with your mouse, I always used USE/COMBINE/DISMANTLE. Again, make it somehow clear how players can interact with the environment. Nothing is more frustrating for me to see some interaction being the solution to a problem, which would be trivial to do IRL but that was apparently not available to me.
5) When I selected to start the game (download, not in browser) as 1900 x 1080 fullscreen (the resolution of my primary monitor) during the Unity startup, the unity logo screen would be fullscreen, but the game would revert to 1900 x 1080 *windowed*. The same is true for using smaller fullscreen resolutions.
Again, I really liked this. I'm not much of a horror fan, but the story of Mark, as told through the collectables and starting with his childhood room, is interesting for me.