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