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