Here is the full list of all 10 Lurk in the Dark : Prologue achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
At a specific timing, try to peek under the closed door in the restroom.
After winning all achievements, watch a credit.
Try pressing the shutter button in annex.
Collect all items and files in one game play.
Enter the residence.
After entering the residence, try to return from the door behind you.
Solve the mystery of the desk.
Something under the bed......Hmm...
After the crying stopped, look into the hole in the wall again...
Move forward without fear.