Here is the full list of all 34 The Book of Unwritten Tales: The Critter Chronicles achievements.
Make the baby critter fly 3 times.
Finish the fifth chapter in normal mode.
Let Critter wear every available costume part simultaneously.
Finish the fourth chapter in normal mode.
Let Critter fly 3 times.
Finish the third chapter in normal mode.
Find out the machinists dirty little secret.
Finish the second chapter in normal mode.
Try to climb the tricky stairs 3 times.
Disguise as a lamp 3 times.
Finish the first chapter in normal mode.
Finish the fifth chapter in hard mode.
Find the best disguise for Critter to enter the sanctuary.
Finish the fourth chapter in hard mode.
Slide down the tricky stairs 3 times.
Paint the picture correctly at the first try.
Manipulate the pictures to empty a frame.
Catch Ma'Zaz in a trap.
Finish the third chapter in hard mode.
Join the Black Guards.
Make a penguin cocktail.
Convince Cornelius to lock himself up.
Scare Petra away.
Finish the second chapter in hard mode.
Click stuff 1000 times.
Show Layla the stars.
Break the conveyor belt.
Distract the critter cook.
Hit the penguin 3 times.
Finish the first chapter in hard mode.
Annoy the orc bounty huntress.
Point at stuff 1000 times
Open the captains little chest.
Look at all the outfits in the wardrobe.