Achievements:
     Complete   the   following   achievements  to  unlock  Xbox  Live
Gamerscore points.

Exterminator (10 points)     Defeat the giant spider.
Sharp Shooter (10 points)    Don't waste more than 30% of your bullets.
Unstoppable (10 points)      Finish a zone without losing a life.
Lair Slayer (10 points)      Complete all underground zones.
Annihilator (10 points)      Kill more than 85% of the total 
                             enemies in a zone.
Small Arms Expert (20 pts)   Finish a zone without using grenades 
                             or nukes.
Twin Medal (20 points)       Finish a zone in Co-op mode.
Speed Freak (20 points)      Finish a zone in less than 15 minutes.
Peace Maker (20 points)      Finish a zone killing less 
                             than 50% of the enemies.
Tricked Out (20 points)      Max out all of the vehicle power-ups.
Survivor (20 points)         Finish a zone killing 60% 
                             of the units on foot.
Assault Hero (30 points)     Complete the game.