Complete the following achievements to unlock Xbox Live Gamerscore points.

Adventure Story Complete: Complete Adventure Story mode.
Adventure Story Gold: Complete Adventure Story mode with all gold medals.
Survivor: Earn a gold medal in the Survival scenario.
War Story Complete: Complete the War Story.
War Story Gold: Complete the War Story with all gold medals.
Eight-Port Master: Earn a gold medal in The Eight-Port Challenge scenario.
Fed And Entertained: Completed Adventure Story mode Chapter 8 (Military Madness).
Honorary Fish: Complete Adventure Story mode Chapter 10 (Deja Vu).
Marksman: Complete War Story mode Mission 4 (Into The Warp).
Max Power: Get Max Power to help in War Story mode Mission 6 (The Attack).
Sir Protector From Asteroids: Complete the Hammer Scenario.
Friend Of Wally: Built a habitat for Wally.