Here is the full list of all 14 Milo's Quest achievements.
Defeat the third Boss
Open 10 treasure chests.
Solve 20 puzzles.
Defeat the second Boss.
Defeat 100 enemies.
Open 5 treasure chests.
Solve 10 puzzles.
Defeat 50 enemies.
Defeat the first Boss.
Defeat 25 enemies.
Solve 5 puzzles.
Get 50 bones.
Get 25 bones.
Open 1 treasure chest.