Thanks for playing!
Just so you know: There is Prologue (Corridor, Treasury, Long Corridor), Act 1, Act 2, Act 3, The End.
All doors in the prologue zone can be opened. Just pay attention to signs and sounds.
Some doors are activated after you do smth else. "The Door" is written in quotes for a purpose, later you see another sign that says smth about "The Door" :)
You get "The End" when you reach it, as it says it on the screen.