Here is the full list of all 12 Haunt achievements worth 200 gamerscore. It takes around 3-4 hours to unlock all of the achievements on Xbox 360.
Complete the game without using a Vitality Vial
Complete the game
Retrieve the Phantaflask from the Auditory Annex and return it to the statue
Collect every newspaper clipping
Successfully avoid 5 Charger ghost attacks
Answer the ringing telephone
Defeat one of each type of ghost
Retrieve the Phantaflask from the Luminarium and return it to the statue
Pose for a photo and then admire the picture
Retrieve the Phantaflask from the Motility Vaults and return it to the statue
Star in a motion picture
Retrieve the first Phantaflask and return it to the statue