Here is the full list of all 16 Tiny Knight achievements.
Forest Guardian Defeated
Humble Beginnings: Gold Completion
Verdenn Forest: Gold Completion
The Cavern: Gold Completion
The Dungeon: Gold Completion
The Mountain: Gold Completion
The Snowy Peak: Gold Completion
The Slimy Way Down: Gold Completion
The Mountain Cells: Gold Completion
Enemy Mines: Gold Completion
Lake City: Gold Completion
Malicious Pit: Gold Completion
The Graveyard: Gold Completion
Mountain Guardian Defeated
Dragon Mother Defeated
Skeleton King Defeated