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