All weapons unlocked. Unlimited health.
Survive as many levels as possible by killing all the enemies in each level.
You get points for each enemy you kill. If you kill an enemy with a weak weapon you will get more points that if it where a powerful weapon.
Levels: There are 30 levels in total.
Enemies: There are 9 types of enemy. As the game progresses more challenging enemies are introduced.
Weapons: There are 9 types of weapon. You can collect new weapons from the enemies that you kill.