Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Big Hitter (50 points)	Get a score of 50,000 in Bodycount in one game.
Houston We Have a Problem (75 points)	Complete all Alien Invasion missions.
Let the Bodies Hit the Floor (50 points)	Kill 250 worms in Bodycount.
Living in the Future (25 points)	Use all of the alien weapons.
Not a Scratch (50 points)	Don't allow the UFO to take any damage in level 6.