Chikyū Kaihō Gun ZAS is a vertical scrolling shooter video game developed and published by T&E Soft for the Nintendo Game Boy exclusively in Japan on December 18, 1992.
Sometime in the 21st century, humanity leaves Earth for Mars due to a legacy of environmental pollution on their home planet. Nobody inhabited the Earth until a group of super-intelligent robots from another galaxy suddenly took over. They have changed the once-proud planet into something that they can inhabit on. An impromptu liberation army was set up to save the planet from the robots; who somehow got rid of the pollution on Earth.
The gameplay is done in a style similar to Gradius and R-Type.
Players proceed through the game; shooting enemies while dodging obstacles and collecting power-ups for their shooting weapons. The game uses the basic configuration for the ship's control; with one button doing the shooting. As a complex scrolling shooter, this game attempts to emulate multiple dimensions using the limitations of the Game Boy console.