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