Here is the full list of all 36 Full Metal Furies achievements.
Complete the game (true end) on NG+
Unlock every piece of equipment for every Class
Find All Monolith Stones in the Stygian Well
I always wanted a sibling
Unlock every item in the Treasury
See the World
Defeat Titan King Prometheus
Unlock Cerby
Make a choice
Enter the Cave
Solve the Last Puzzle
Solve the Third Puzzle
Find all Monolith Stones in the Desert of Atlantis
Solve the Fifth Puzzle
Complete all Class challenges
Solve the Fourth Puzzle
Appease Ferryman Charon
Have 1 point in every skill for 1 Class
Destroy the World
Defeat Planetar Cronus
Defeat Sky Sniper Lelantos
Solve the Second Puzzle
Air crit an enemy 5 times in a row
Solve the First Puzzle
Crack the code for at least 1 Computer
Find and translate all Monolith Stones in Thessaly
Find and translate all Monolith Stones in the Foloi Forest
Find all Monolith Stones in Tartarus
The synopsis looks grim
Defeat Land Fortress Coeus
Master a piece of equipment by reaching its max level
Defeat Wavebreaker Meneotius
Earn 1 level in your equipment
Find your first Monolith Stone
Unlock Go-Cat
Unlock your first piece of equipment