The story begins deep in the solar system, past the planet Neptune. You have plotted your course to planet Earth, and are now on your way home. But this won't be any pleasure cruise. Aliens are on the attack, swarming around your ship and forming cavalries to block your way. Fortunately you've come prepared for this sort of thing. Grab your joystick and keep your finger on the trigger, because it's time to go blasting!
Each stage of Gyruss begins with swarms of alien ships moving around you, before settling into a formation ahead of you in space. These swarms are your chance to pick off as much of the alien convoy as you can before the battle really begins. Be careful though; even while swarming these aliens will often shoot back, and sometimes they will go kamakaze! Once in formation, the aliens will periodically break off and come flying back towards you, often zig-zagging their way through space, returning fire while dodging your shots. If you survive long enough to destroy the entire convoy, you move just a little closer to your goal, where new swarms of aliens await!
Once every stage, a group of rogue satellites joins in the fun. These satellites are anything but harmless, taking shots at you as they hover distractingly in front of your ship. However, they are also your key to a very valuable power-up. If the middle satellite is in the shape of a sphere, shooting it will unleash two energy orbs, spinning around the perimeter of your ship's path. Catch these orbs for an extra laser cannon and twice the fire power! Once earned, the power-up is yours to keep until you lose your ship. As long as you have the power-up, the satellites are simply a way to earn extra points. But if your current ship is destroyed, the spherical satellite will eventually appear again... if you can live that long!
As if battles with aliens aren't enough, the way to Earth is littered with asteroids. The closer to Earth you get, the more and more they appear. Dodge these big space rocks, because you can't shoot them and you certainly can't fly through them!
At the end of stage 2, and then every four stages afterward, you will reach the next planet in the solar system. You then have a brief moment to relax with a "chance" stage. In these stages, the aliens fly in fancy patterns, challenging you to pick them off without fear of counterattack. Destroy all 40 aliens in a "chance" stage for even more bonus points!
Survive long enough, and you will finally reach your home planet of Earth. But that doesn't mean the game is over. Soon you're back past Neptune to try again on a much more perilous journey! Good luck!