Here is the full list of all 15 Gemini Rue achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete the game once in Commentary mode
Complete all fights without losing any health
Find all 4 hidden Easter Egg Characters
Find all 6 hidden notes in Center 7
Complete all Center 7 Exams without any strikes
Find all 3 extra ammo magazines
Take the stairs instead of the elevator
Find all Database Articles
Access the Memory Database in the Director’s Office in Center 7
Complete the game once
Escape Center 7 without losing any health
Analyze a photo using the terminal
Heal the fellow Man on Barracus
Be able to control both Azriel & Delta-Six
Evade the Boryokudan rather than fight them