Here is the full list of all 8 Defy Gravity Extended achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Enter the Gauntlet
Prove yourself as a Gravitymancer Warrior
Prove yourself as a Master Gravitymancer
Prove yourself as a Grand Master Gravitymancer
Prepare yourself for the real Gauntlet
Transcend all Gravitymancers and become The One
Prove yourself as an Apprentice Gravitymancer
Prove yourself as the Gravitymancer Emperor