Here is the full list of all 12 OPEN DOOR achievements.
See the first appearance of the monster
Solve the puzzle with bricks
Open the cells in the correct order
Turn on the lights in all rooms
Turn off all radios in one playthrough
Look into every toilet
Find the code from the old archive using the hints in the notes on the table.
Read all files
Solve riddles with books
Throw it right into the switch
Solve the riddle
Start a Story