Here is the full list of all 21 Occult achievements.
start a game together
mirror quest finished
killed the Spiderlady
25 window jumps
big bang
collected 10 jewelry
kill mediums
died from the fall
open lockers and drawers 50 times
throw a friend out of the cupboard 5 times
sat in the closet for more than a minute
5 minutes to stand by the car
first time stunned by a monster
helped a friend get up
caught 25 spiders
complete the game alone
start a four-player game
found the phone and answered the call
open 3 locked doors
kill with train
defeat the evil