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