Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Chapter Eight (10 points)	Complete the final checkpoint in Into the Depths on Normal or High Difficulty.
Chapter Eleven (10 points)	Complete the final checkpoint in Red Sky on Normal or High Difficulty.
Chapter Five (10 points)	Complete the final checkpoint in Street Fight on Normal or High Difficulty.
Chapter Four (10 points)	Complete the final checkpoint in Road Home on Normal or High Difficulty.
Chapter Nine (10 points)	Complete the final checkpoint in Enlightenment on Normal or High Difficulty.
Chapter One (10 points)	Complete the final checkpoint in Vanguard Down on Normal or High Difficulty.
Chapter Seven (10 points)	Complete the final checkpoint in Edge of the World on Normal or High Difficulty.
Chapter Six (10 points)	Complete the final checkpoint in Road to Hell on Normal or High Difficulty.
Chapter Ten (10 points)	Complete the final checkpoint in Reveal on Normal or High Difficulty.
Chapter Thirteen (10 points)	Complete the final checkpoint in Reversion on Normal or High Difficulty.
Chapter Three (10 points)	Complete the final checkpoint in Breakout on Normal or High Difficulty.
Chapter Twelve (10 points)	Complete the final checkpoint in Deja Vanguard on Normal or High Difficulty.
Chapter Two (10 points)	Complete the final checkpoint in Caged on Normal or High Difficulty.
Meet Your Master (15 points)	Defeat The Prophet Kiltehr (Any Difficulty).
The Collector (10 points)	Defeat The Slave Driver (Any Difficulty).
The Great Destroyer (10 points)	Defeat The Brute (Any Difficulty).
The Tin Man (10 points)	Defeat The Butcher (Any Difficulty).