The Episode 3: The Sword in the Darkness Add-on for Game of Thrones: A Telltale Games Series (Xbox 360) has 8 achievements worth 160 gamerscore.
Complete Episode 3.
Complete Chapter 7 of Episode 3
Complete Chapter 6 of Episode 3
Complete Chapter 5 of Episode 3
Complete Chapter 4 of Episode 3
Complete Chapter 3 of Episode 3
Complete Chapter 2 of Episode 3
Complete Chapter 1 of Episode 3