Here is the full list of all 12 Terror At Oakheart achievements.
Complete the Prologue Chapter.
Kill Teddy as Ashley.
Complete chapter one.
Complete Chapter Two.
Complete Chapter Three
Complete Chapter Four
Defeat Scout Master Beaver.
Complete Chapter Six
Complete Final Chapter.
Complete Mr Tops Murder Mayhem
Complete Chapter Seven.
Collect all of Teddy's plushie, visit his playroom and activate each one.