Accomplish the indicated achievement to get the corresponding number of 
Gamerscore points:

Jitterbug (20 points): Clear the game in 60 minutes or less. 
Invincible (30 points): Clear the game without dying. 
Almost Invincible (20 points): Clear the game without continuing. 
No Coffee Break (10 points): Clear the game without using any Energy or Mystery Tanks.
Peacekeeper (20 points): Clear the game by defeating the fewest number of enemies possible.
Conservationist (20 points): Clear the game by using the least amount of Weapon Energy possible.
Gamer's Day (20 points): Clear the game 5 times in 1 day. 
Whomp Wily! (5 points): Clear the game once. 
Destroyer (20 points): Defeat your 1000th enemy. 
World Warrior (5 points): Defeat every type of enemy. 
Trusty Sidearm (20 points): Defeat the 8 Bosses with the Mega Buster. 
Blue Bomber (10 points): Defeat a Boss without getting damaged.