Here is the full list of all 13 Pixel Art Coloring Book achievements.
Color the entire Animals category.
Color the entire Architecture category.
Color 10 hard pictures.
Color the entire Food category.
Use Magic wand 5 times.
Use Bomb 5 times.
Use Color splash 5 times.
Color 10 medium pictures.
Color 10 easy pictures.
Color 3 pictures without using boosters.
Use Tornado 1 time.
Color your first picture.
Open the game