Achievements:
Complete the following achievements to award the indicadeted amount of
Xbox Live Gamerscore gamerscore points.

Unstoppable (10 gamerscore points):
Complete a zone without losing a life.

Sharp Shooter (10 gamerscore points):
Don't waste more than 30% of your bullets.

Lair Slayer (10 gamerscore points):
Complete all underground zones.

Exterminator (10 gamerscore points):
Kill the giant spider.

Annihilator (10 gamerscore points):
Kill more than 85% of the total enemies in a zone.

Twin Medal (20 gamerscore points):
Complete a zone in Co-op mode.

Tricked Out (20 gamerscore points):
Max out all of the vehicle power-ups.

Survivor (20 gamerscore points):
Complete a zone killing 60% of the units on foot.

Speed Freak (20 gamerscore points):
Complete a zone in less than 15 minutes.

Small Arms Expert (20 gamerscore points):
Complete a zone without using nukes or grenades.

Peace Maker (20 gamerscore points):
Complete a zone killing less than 50% of the enemies.

Assault Hero (30 gamerscore points):
Complete the entire game.