Here is the full list of all 14 BiT Evolution achievements.
Find any hidden area within the game
Complete a level without killing any enemies (not even bats!)
Defeat the boss of World 1
Obtain a gold star on any level
Collect all of the pixels in the game
Defeat the game's final boss
Complete 20 levels in the game's challenge mode
Obtain a gold star on any 10 levels
Defeat the boss of World 2
Defeat the boss of World 3
Defeat the boss of World 4
Survive 30 seconds with the "death wall" in level 1-11
Complete a level without ever entering the Realm of Code
Carry the first Spider Clam to the goal tape on level 3-11