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