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.
Solve the mystery of the desk.
Try pressing the shutter button in annex.
After the crying stopped, look into the hole in the wall again...
Collect all items and files in one game play.
Move forward without fear.
After winning all achievements, watch a credit.
Enter the residence.
After entering the residence, try to return from the door behind you.
Something under the bed......Hmm...