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