Here is the full list of all 32 Deadlings: Rotten Edition achievements.
Finish 20 levels without killing a single zombie.
Collect 800 brains.
Kill the zombie with the other zombie.
Discover a deadly lasers.
Unlock the Lazybrain.
Complete phase 1.
Complete level 14 in less than 10 seconds.
Collect 50 stars.
Kill over 100 zombies.
Unlock the Gasfat.
Collect 400 brains.
Complete level 04 using one zombie.
Complete 5 levels in Nightmare Mode.
Collect 150 brains.
Unlock the Creep.
Complete phase 2.
Complete phase 3.
Complete phase 4.
Discover an awesome portals!
Discover a freezing freezers.
Discover a crazy mutators.
Complete all levels in Nightmare Mode with maximum rank.
Complete 20 levels in Nightmare Mode.
Complete 45 levels in Nightmare Mode.
Complete 60 levels in Nightmare Mode.
Collect 100 stars.
Collect 150 stars.
Collect 200 stars.
Complete all levels in Normal Mode with maximum rank.
Complete all bonus levels.
Complete all bonus levels with maximum rank.
Complete bonus level 10.