Here is the full list of all 50 Game of Thrones achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Lose the final battle
Finish Alester's story
Chapter 15: execute the judgement passed down on the Westfords
Finish Mors' Story
Gain all the skills linked to the dog with Mors
Reach the maximum level
Finish chapter 15
Finish chapter 14
Complete all the secondary objectives of the story
Finish chapter 13
Send 10 recruits to the Wall with Mors
Chapter 13: reach Jeyne's room without ever being seen
Kill 400 enemies
Finish chapter 12
Chapter 12: take back Riverspring with a total victory
Learn all skills within a character's stance tree
Finish chapter 11
Chapter 11: bring an end to the trial by combat in under 2 minutes
Finish chapter 10
Finish chapter 9
Finish chapter 8
Emerge triumphant in the final arena combat
Seize the three objects of value from the Collector with Alester
Chapter 8: find the key in Alester's father's tomb
Mete out 5 deathblows
Convince Bethany to return to Chataya's brothel with Alester
Find 10 secrets with the vision of R'hllor
Finish chapter 7
Kill 10 enemies with Mors' dog in skinchanger mode
Finish chapter 6
Chapter 6: don't lose pursuit of the bastard
Finish chapter 5
Finish chapter 4
Acquire 1 golden dragon
Finish chapter 3
Use Mors' dog's sense of smell to find 5 secret objects
Finish chapter 2
Chapter 2: protect the people with Alester
Finish chapter 1
Chapter 1: confront the four recruits during the training session with Mors
Chapter 2: protect the nobility with Alester
Chapter 7: find all the corrupt brothers of the Night's Watch
Chapter 7: attack the camp without killing the sentries at the start
Chapter 8: save Orys from the City Watch
Chapter 9: kill 6 of Lord Harlton's soldiers during the fight at dinner
Chapter 9: suffer all the physical abuse during the torture sequence
Chapter 14: come to the aid of the Reapers
Find all the statues of the Seven
Finish the game without a single ally (except Mors and Alester) being KO'd
Gain all the skills linked to R'hllor's fire with Alester