Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Clear zone 1 on Easy (60 points)	Clear all levels in zone 1 on Easy.
Clear zone 1 on Normal (160 points)	Clear all levels in zone 1 on Normal.
Clear zone 2 on Easy (80 points)	Clear all levels in zone 2 on Easy.
Clear zone 2 on Normal (180 points)	Clear all levels in zone 2 on Normal.
Clear zone 3 on Easy (100 points)	Clear all levels in zone 3 on Easy.
Clear zone 3 on Normal (200 points)	Clear all levels in zone 3 on Normal.
Decakill (40 points)	Kill ten or more zombies with a shot.
Double kill (20 points)	Kill two or more zombies with a shot.
Eradicator (50 points)	Kill fifteen or more zombies with a shot.
Pentakill (30 points)	Kill five or more zombies with a shot.
Terminator (70 points)	Kill twenty or more zombies with a shot.
Zombie killer (10 points)	Kill one or more zombies.