something troubles me.

[Googolplex]

This is why developers should do more hidden levels.
Levels what you don't find when playing the game normal.
There should be a secret mechanism for example what will open a hatch into a new dark cellar, what nobody could find out at now. So, when you mean you played the game and have all seen, you think wrong.
There is something you haven't seen. And so, Amnesia would be a game with more secrets and hidden stuff (like completely new levels) which are optional results of experimental success.
For example, the player tries something with the physics, putting a box onto a shelf, so the shelf breaks down and opened a new unknown hole.
This is what games make interesting to play ever and ever, find out new things after many years and a game where you never could see all secrets. So complex ideas what are not part of the game, but optional for advanced players only.