Here is the full list of all 14 BiT Evolution achievements.
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 level
Obtain a gold star on any 10 levels
Defeat the boss of World 1
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
Find any hidden area within the game
Complete a level without killing any enemies (not even bats!)
Complete a level without ever entering the Realm of Code
Carry the first Spider Clam to the goal tape on level 3-11