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