Here is the full list of all 12 Poltergeist: A Pixelated Horror trophies - there are 7 bronze, 4 silver and 1 gold.
Finish the time trial mode in less than 90 minutes.
Beat all of The Boss' levels.
Finish all the Office Era levels (No boss).
Activate the secret glitched objects
Finish all the Modern Era levels (No boss).
Unlock the Office Era levels.
Beat all Reverend Morris' levels.
Beat all Nicole K.'s levels.
Finish all the Eighties Era levels (No boss).
Beat all of Larry Zuchini's levels.
Finish all the Classic Era levels (No boss).
Beat your first level in the game.