Here is the full list of all 66 Last Command achievements.
Read through the entire credits
Completed story mode
Defeated the ultimate evil with Fei
Defeated "it"
Defeated "it" on Expert Mode
Defeated "it" on Nightmare Mode
Recovered Fei's data file from the recycling bin
Removed your name from the Ban List
Quit the game in a collapsing world
Kept trying to continue the game in a collapsing world
Completed the fourth chapter in story mode
Defeated Algor Hime
Defeated Algor Hime on Expert Mode
Defeated Algor Hime on Nightmare Mode
Defeated Tyrant - ??.ver
Defeated Tyrant - ??.ver on Expert Mode
Defeated Tyrant ??.ver on Nightmare Mode
Collected all modules in story mode
Defeated Tyrant
Defeated Tyrant on Expert Mode
Defeated Tyrant on Nightmare Mode
Defeated Samurai
Defeated Samurai on Expert Mode
Defeated Samurai on Nightmare Mode
Defeated Master Tao
Defeated Master Tao on Expert Mode
Defeated Master Tao on Nightmare Mode
Defeated Simulant - Thousand Faces
Defeated Simulant - Thousand Faces on Expert Mode
Defeated Simulant - Thousand Faces on Nightmare Mode
Got an EPIC rating on any boss
Defeated Simulant - Origin
Defeated Simulant - Origin on Expert Mode
Defeated Simulant - Origin on Nightmare Mode
Defeated Simulant - Samurai on Expert Mode
Defeated Simulant - Samurai on Nightmare Mode
Defeated Simulant - Samurai
Defeated Thousand Faces
Defeated Thousand Faces on Expert Mode
Defeated Thousand Faces on Nightmare Mode
Defeated Publicity Official - The Truth
Defeated Publicity Official - The Truth on Expert Mode
Defeated Publicity Official - The Truth on Nightmare Mode
Defeated Publicity Official - Gardening
Defeated Publicity Official - Gardening on Expert Mode
Defeated Publicity Official - Gardening on Nightmare Mode
Defeated Publicity Official - Melody on Expert Mode
Defeated Publicity Official - Melody on Nightmare Mode
Defeated Publicity Official - Melody
Continue or restart challenge from failed for 100+ times
Defeated Iron Guard Knight - Origin
Defeated Iron Guard Knight - Origin on Expert Mode
Defeated Iron Guard Knight - Origin on Nightmare Mode
Defeated Iron Guard Knight - Lancelot
Defeated Iron Guard Knight - Lancelot on Expert Mode
Defeated Iron Guard Knight - Lancelot on Nightmare Mode
Dashed more than 1000 times
Defeated Iron Guard Knight - Gawain
Defeated Iron Guard Knight - Gawain on Expert Mode
Defeated Iron Guard Knight - Gawain on Nightmare Mode
Defeated Iron Guard Knight - Bedivere on Expert Mode
Defeated Iron Guard Knight - Bedivere on Nightmare Mode
Defeated Iron Guard Knight - Bedivere
Continue or restart challenge from failed for 10+ times
Dashed more than 100 times
Started story mode for the first time