Your mission is quite simple: kill as many enemies as possible, while trying to stay alive. First, you must escape from Earth, to visit five planets and get a part of the Genesis on each one. Once you have successfully assembled the spaceship, you will use it to get back to Earth and free us from the Dork menace.
Your ship has two different shoot types: normal shoot, which will be used to fire the weapons equipped by your ship at any time, and a megablast, which will kill every enemy around you. To activate the megablast, keep the fire button pressed, until the power bar located on the lower-right side of the screen is filled up. The blast will be launched when you release the fire button. You have an unlimited number of normal shoots and a very limited amount of available megablasts, so use them wisely.