Here is the full list of all 31 Tiny Thief achievements.
Take a nap while you hide away
Drop 3 gnome statues
Gain three stars on all levels of the 'Bewitched' story
Find all the secrets in the Treasure Chest
Get at least one star in all levels of the 'Bewitched' story
Create all types of red candy
Play the piano three times
Get at least one star in all levels of the 'Rattling Bones' story
Gain three stars on all levels of the 'Rattling Bones' story
Complete 20 levels without using the Hint Book
Gain three stars on all levels of the 'A Royal Rescue' story
Get at least one star in all levels of the 'A Royal Rescue' story
Find a rat hidden in a chest
Play one level for more than 20 minutes
Get at least one star in all levels of the 'The Cursed Treasure' story
Gain three stars on all levels of the 'The Cursed Treasure' story
Open the shower curtain 3 times
Get at least one star in all levels of the 'A Corrupt Sheriff' story
Gain three stars on all levels of the 'A Corrupt Sheriff' story
Complete 10 levels without using the Hint Book
Pop a bubble gum 3 times
Get at least one star in all levels of the 'A Rumbling Stomach' story
Gain three stars on all levels of the 'A Rumbling Stomach' story
Complete 5 levels without using the Hint Book
Complete 1 level without using the Hint Book
Gain all the stars on all levels of the 'First Lessons' story
Get at least one star in all levels of the 'First Lessons' story
Throw a bucket into a guard's head
Open the credits screen
Steal 5 pies
Use all the doors in the level