Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Admiral (80 points)	Get at least 100 stars in the campaign.
Captain (50 points)	Get at least 60 stars in the campaign.
Curious (30 points)	Try each of the arcade modes at least once.
Death Proof (80 points)	Beat every level without dying.
DieHard (10 points)	Beat a level without dying.
Ensign (30 points)	Get at least 40 stars in the campaign.
Excavator (50 points)	Find all secrets in the campaign.
First Impressions (10 points)	Kill 50 enemies.
Hidey-Hole (10 points)	Find a secret area.
Pacifist (20 points)	Complete 5 levels without firing a shot.
Rookie (10 points)	Get at least 20 stars in the campaign.
Xenocide (20 points)	Kill all enemies in 5 levels.