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