Complete the following achievements to unlock Xbox Live Gamerscore points.

Alien in Training (5 points): Complete level 1-1. 

Hungry Yeti (10 points): Eat 50 KGB Agents with the Yeti. 

City Destroyer (10 points): Destroy 25 buildings during one game. 

Juvenile Alien (10 points): Complete the game on the Easy difficulty. 

Adult Alien (15 points): Complete the game on the Medium difficulty. 

Expert Alien (20 points): Complete the game on the Hard difficulty. 

Head Chomper (20 points): Head bite 50 enemies without touching the ground or firing. 

Killing Spree (15 points): Kill 1,000 enemies during one game. 

Mad Hatter (20 points): Unlock all 31 hats. 

Perfect Flight (30 points): Defeat the final Boss without using a continue. 

Survivalist (25 points): Survive any challenge mode for 20 minutes. 

WMD (20 points): Reach 5000 km in Super Soviet Missile Master.