ModRetro Revives a 33-Year-Old Japanese Game Boy Exclusive on Cartridge

Released in Japan in December 1992, Chikyū Kaihō Gun ZAS (roughly translating to “Earth Liberation Army ZAS”) never saw an international launch, remaining a Japanese exclusive. This scarcity turned its limited cartridge run into one of the most coveted titles in the entire Game Boy library. While collecting games is enjoyable, ModRetro believes they are meant to be played, not just displayed behind plastic. Therefore, they have decided to re-release this sought-after vertical shooter for their Game Boy-inspired Chromatic handheld console, making it accessible to a new generation.

Developed and distributed by T&E Soft, this vertical 'shooter' pushed the original Game Boy hardware beyond its perceived limits. The game featured impressive visual depth, with drifting planets and shooting stars crossing your flight path in the background. Foreground elements stood out clearly, ensuring players always knew where they could fly and what was attacking them. For a console with a small, monochrome screen, the visual fidelity was—and remains—truly incredible.

What makes the gameplay of Chikyū Kaihō Gun ZAS so addictive is its unique satellite mechanic. Your ship can expand, splitting its fire to cover a wider area at the cost of concentrated damage. Retract it for precise and devastating shots. The game cleverly teaches you this on the fly. Through mini-bosses that deflect bullets with their hands or enemies hiding in inaccessible angles, you quickly learn exactly when to expand your fire and when to counter-attack with focused precision. It's a simple switch that generates genuinely tactical decisions, adding significant depth to the gameplay.

Furthermore, the soundtrack alone justifies the purchase of the cartridge. Light and adventurous in the initial levels, it becomes darker and faster as the difficulty increases. This is precisely the type of game that helped solidify ‘chiptune’ as a recognized musical genre, leaving a lasting impact on gaming audio.

Over decades, ZAS slowly found its audience through importers, emulation communities, and word-of-mouth. By the time collectors realized its value, original cartridges had become extremely rare and expensive. Now, ModRetro offers this classic for $45 USD on its official website. With infinite replayability, this re-release ensures that a new generation of players can experience its challenges and compete, all on authentic hardware—be it a Chromatic, an Analogue Pocket, or an original Game Boy.