Accomplish the indicated task to get Gamerscore points:

Mad Cat Skillz: Get nine lives. 
Multitastic: Get a 10x multiplier. 
Pacifism: Survive the first sixty seconds without shooting or using a bomb. 
Quartermaster: Collect nine bombs. 
Score 100,000: Get 100,000 points. 
Score 250,000: Get 250,000 points. 
Score 500,000: Get 500,000 points. 
Score 1,000,000: Get 1,000,000 points. 
Survive 100,000: Get 100,000 points without losing a life. 
Survive 250,000: Get 250,000 points without losing a life. 
Survive 500,000: Get 500,000 points without losing a life. 
Survive 1,000,000: Get 1,000,000 points without losing a life.