Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
A Friend In Need ( 10 points )	Tried to save Chen.
Cutting Off Heads ( 10 points )	Defeated the Nightcrawler commander.
First Encounter ( 10 points )	Defeat the first Nightcrawler Elite.
While You're Down There ( 10 points )	Kill 10 critters such as rats and crows in the Perseus Mandate campaign.
You Must Be on the Team ( 5 points )	Watch the Perseus Mandate campaign entire credits.