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