In my perception of things, there is a difference between "horror" and "scary". Whenever something scary happened in Amnesia, to me, it had to be related to an element of surprise, an unexpected event that I would not want to face or confront
instinctively (meaning it's out of my conscious control). It's a "concrete" interaction. Objectively, as far as the developers are concerned, yes it is intent, but playing a game in an objective perspective kills the personal experience. It's gotta be something you have to deal with, not an "intent to scare me".
On the other hand, horror wasn't really something related to a particular event. It was a condition, while walking inside the castle and going through its halls. It's me filling the void with my own fears (fear of the unknown), which is — perhaps — the perfect definition of immersion. Like a setup wizard, I install that horror by... clicking on it (lol Amnesia.exe) ! The atmosphere in the game is so successful it interacts with our
psychological archetypes. To me, that is the essence of your gameplay experience simply because... you are creating it !
It's not a wild guess to say that 'immersion' depends of the sensitivity of each person; for some people immersion requires a conscious decision, for some (most) people the immersion happens subconsciously while playing the game and some other people can't even care about the idea of a "horror game" and can't even immerse themselves to it. Essentially, we make it a horrifying experience. It's our intent, whether we even like it or not. We fill in some of our worst fears (shadow) and hope to deal with 'em and get through (faith). It's a great duality.
I am more than certain
Amnesia : A Machine for Pigs will be able to provide that experience better than it was on
Amnesia : The Dark Descent.