It is set in the middle of the 21st century. The armies of Lord Halley are launching attacks on planet Earth using Halley's Comet as the spearhead of the attack. The player represents the last chance for Earth piloting a craft specially developed to engage the enemy hordes. The game has six long stages set in locations in space such as above planets, inside enemy vessels or in asteroid fields. There is always a big boss at the end of each stage each with its own weakness. There are power-ups, which can be picked up along the way when the player shoots particular asteroids or satellites. These upgrade their weapon strength, speed, shields and add small drone wingmen ships which assist in firing. The enemies mostly attack in waves with similar types of vessel attacking together in formation.