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