Here is the full list of all 9 The Haunting of Billy achievements.
Find your way off the level.
Have on you 250 candy at one time.
Meet your loving and caring guardian demon.
Blow an enemy clean off the level.
Don't take Bucky with you.
Wear a full costume set.
Look at that lil' devil!
Wear a full costume where every piece is unique.
Find and equip Bucky's pan.