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