Here is the full list of all 13 Doorways: Prelude achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Collect all Relics
Pickup all notes
Collect all Relics of Marble from The Cave
Collect all Relics of Metal from The Forest of Stakes
Finish Chapter 2
Collect all relics of Bronze from The Auditorium
Pickup all notes from The Auditorium
Find all Museum paints
Finish Chapter 1
Pickup all notes from The Forest of Stakes
Find all Torture sketches
Finish the Tutorial
Collect your first Relic