Here is the full list of all 19 Stewart The Fox achievements.
Find all collectable TV's.
Find all collectables throughout the game!
Find all collectable Orb's.
Find all collectable Gifts.
Finish the fourth level to get this achievement
Finish level 4 in under 3.5 minutes!
Kill the second boss in level 4
Kill 100 Enemies.
Finish the third level to get this achievement
Finish level 3 in under 3.5 minutes!
Kill the first Boss in level 3
Kill 75 Enemies.
Finish level 2 in under 3.5 minutes!
Finish a level without dying.
Kill 50 Enemies.
Kill 25 Enemies.
Finish the second level to get this achievement
Finish the first level to get this achievement
Finish level 1 in under 3.5 minutes!