Here is the full list of all 18 TukTuk achievements.
Beat the Game on Kindergarten Difficulty
Beat the Game on Normal Difficulty
Beat the Game on Hardcore Difficulty
Beat the Game on Nightmare Difficulty
Beat the Game on Impossible Difficulty
Collect all Lua Drops
Beat the Game never hitting an Enemy
Use a Cheat
Die 1000 times
Kill 50 enemies
Buy Nothing
Never open the Shop in one Playthrough
Beat the Game in under 20 Minutes
Max out Everything that is maximizable
Skip all Cutscenes once
Achieve the Grappling Hook
Achieve the Sword
Achieve the Laser