Here is the full list of all 24 Ghostory achievements.
Play through the first stage
You said you needed ONE Mydrith!
Fail to change into human for the 20th time
Play through the second stage
Play through the third stage
Discover things of the past
Finish the game
Help 9 ice frogs get home
All in all it's just another pond in the wall
Complete a level without stepping in a puddle
Stumble upon worrisome sightings
Complete the tutorial
Meet an old acquaintance
Find out the truth
Escape from the monk
Tramp on the roof
Complete all levels (don't skip any)
Help ice frog find true love
Exit a level with a key in the backpack
Help an ice frog get home
Put a box on a backpack. Yeah, maybe that will help.
Collect 5 Dul'nahari chalices
Stop trying please
Push a box out of a level