Here is the full list of all 16 Plith achievements.
Complete the first world.
Destroy 50 gears.
Place 100 gears.
Use a small gear first time.
Destroy 10 gears.
Use a middle gear first time.
Destroy a gear with dynamite first time.
Finish the first puzzle.
Use a big gear first time.
Complete the second world.
Complete the third world.
Complete the fourth world.
Complete the fifth world.
Place 500 gears.
Complete the game without losing in any level.
Start a new game and complete it without saving/closing the game.