Here is the full list of all 12 Alter World achievements.
Complete 40 Levels
Complete 30 Levels
Complete 20 Levels
Forever gone to Alter!
Complete 10 Levels
Brave enough? die 100 times!
Meet developer!
Complete 50 Levels
finish game with first ending
Finish game with second ending
Jump! Jump! Jump!...and again Jump!
last death!