Taking place in the year 2191, the player pilots a recently developed space fighter, the SR-91, through six stages to defend the Earth from a two-year-long alien invasion. The SR-91 uses the VAWS (Variable Armor and Weapon System) which uses the Optica Weapon Arms. The Arms shield the ship from top and bottom attacks, provides back-up fire and using its Arm System can be positioned to fire in various angles depending on the current weapon. The SR-91 uses one of three different pick-up weapons: the red "Taikuu Laser", thin red beams that fire straight forward; the yellow "Ring Laser", yellow rings which can be aimed in all directions and provide good coverage; and the blue "Hansha Ball", blue spheres that can be also aimed in all directions and bounce off the walls. The only other pick-up items are Speed Ups and Speed Downs. Extends were set at the first 70,000 points and was added with every 80,000.