Here is the full list of all 15 A Night at the Watermill achievements.
Find the mouse
See the good ending
See the neutral ending
See the bad ending
See all endings
Find the bat
Enter PIN into mobile phone
Look into the mirror
See first flashback
Take the weapon
Use saw on wrist
Escape the first room
Use sharpened saw on barred door
Burn this place down!
Touch-a-touch-me