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.
Chapter 1: confront the four recruits during the training session with Mors
Use Mors' dog's sense of smell to find 5 secret objects
Finish chapter 4
Mete out 5 deathblows
Finish chapter 3
Finish chapter 2
Chapter 2: protect the people with Alester
Finish chapter 1
Finish chapter 5
Finish chapter 6
Finish chapter 7
Finish chapter 8
Finish chapter 9
Finish chapter 10
Finish chapter 11
Finish chapter 12
Finish chapter 13
Finish chapter 14
Finish chapter 15
Finish Alester's story
Finish Mors' Story
Chapter 2: protect the nobility with Alester
Chapter 6: don't lose pursuit of the bastard
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 8: find the key in Alester's father's tomb
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 11: bring an end to the trial by combat in under 2 minutes
Chapter 12: take back Riverspring with a total victory
Chapter 13: reach Jeyne's room without ever being seen
Chapter 14: come to the aid of the Reapers
Chapter 15: execute the judgement passed down on the Westfords
Lose the final battle
Complete all the secondary objectives of the story
Emerge triumphant in the final arena combat
Send 10 recruits to the Wall with Mors
Seize the three objects of value from the Collector with Alester
Convince Bethany to return to Chataya's brothel with Alester
Find all the statues of the Seven
Find 10 secrets with the vision of R'hllor
Acquire 1 golden dragon
Kill 10 enemies with Mors' dog in skinchanger mode
Kill 400 enemies
Finish the game without a single ally (except Mors and Alester) being KO'd
Reach the maximum level
Learn all skills within a character's stance tree
Gain all the skills linked to R'hllor's fire with Alester
Gain all the skills linked to the dog with Mors