Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Battle-hardened ( 25 points )	Single player completed.
Elite Unit ( 25 points )	Single player completed on Elite difficulty.
Exterminator ( 20 points )	Killed 1000 aliens.
Frag-master ( 30 points )	Killed 5 aliens with one Frag Grenade.
Hidden Treasure ( 10 points )	Found all secret collectibles.
Immobilised ( 20 points )	Stunned 5 aliens with one Stun Grenade.
Meat Grinder ( 10 points )	Killed 250 aliens during multiplayer Survivor mode.
More Speed, Less Haste ( 10 points )	'Vengeance' completed in 17 minutes or less.
Seasoned Squaddie ( 20 points )	Completed a level in multiplayer.
Survivor ( 10 points )	Stayed alive for 8 minutes in Survivor mode.
Tank ( 10 points )	Took 500 damage without dying.
The Informed ( 10 points )	Picked up all the logs.