Here is the full list of all 35 Ghostly Matter achievements.
Collect all Power-Ups
Defeat the tentacled monster
Defeat the putrid demon of the swamp
Find the plasma rifle
Say yes to a ride to the Pine Creek swamp
Find the Taser
Sink the monster in the bathtub using the sacred water
Defeat the sub-demon of Tungl
Find the Ouija board and summon a ghost familiar
Find the Sniper Sight Power-Up
You've been smashed by a moving column
Defeat the evil priest
Find the Laser
Defeat the Gravedigger
Stop time using the enchanted hourglass
Kill all enemies using an energy bomb
Find the two parts needed to make up the Anti-Demon Kit
Find the Laser Sight Power-Up
Use the alembic to distill a fine liquor
Find the Ancient Amulet of Fate Power-Up
You made a wish throwing a coin into the well
Find the photo of Michael Graves tomb, where Cletus hid the vanished nickel
Find the flamethrower
Despite the warnings you fell into the Pit of Despair
Complete the prologue
Discover the laboratory's password using the Polterscope
Find the Grimoire Power-Up
With the help of the medium, discover the place where the Black Mirror is hidden
Find all 45 documents
Break all five seals in the Cursed Temple
Find the mega-cannon
Defeat the evil hand and retrieve the tarot deck
Defeat the demon Vargh and recover the Black Mirror
Complete the game
You got to the final scene after the credits