Here is the full list of all 12 Imagine Me achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Defeat Three Bosses
Defeat Two Bosses
Defeat One Boss
Complete One Story Page
Complete 50% of the Challenge Levels
Complete All Challenge Levels
Fall for the 15th Time
Jump on a Trampoline 100 times
Move a Crate. Have an Achievement.
Falling into the Darkness
Pick lock your first door
Begin a Dungeon in Campaign