COMPLETE THE 1ST LEVEL
COMPLETE THE LEVEL WITH THE "UNREAL" SETTING
COMPLETE THE LEVEL WITH THE "HARD" SETTING
OPEN THE 5TH TOWER LEVEL
OPEN THE 6TH TOWER LEVEL
OPEN THE 8TH TOWER LEVEL
OPEN THE 7TH TOWER LEVEL
DESTROY 100 ENEMIES
DESTROY 500 ENEMIES
DESTROY 5000 ENEMIES
DESTROY 2000 ENEMIES
DESTROY 10000 ENEMIES
COMPLETE ALL LEVELS
UPGRADE THE MOST EXPENSIVE WEAPON IN THE GAME TO THE MAXIMUM LEVEL
COMPLETE A SPECIAL LEVEL WITH THE "HARD" SETTING WITHOUT LOSING