Here is the full list of all 14 ALONE? achievements.
Find and Collect the Flashlight
Find and Unlock Ending 1
Find and Unlock Ending 2
Find and Unlock Ending 3
Find and Unlock Ending 4
Unlock the Safe
Replace 3 Piano Keys
Enter the Sewer
Enter the Morgue
Find and Collect the Car Keys
Return the Jesus Statue
Read All Notes
Enter the Basement
Collect all Screws