Originally released in 1992 as a Japanese exclusive, Chikyū Kaihō Gun ZAS became one of the rarest and most technically ambitious shooters on the original Game Boy®. Fast-moving stages are packed with enemy waves and layered scrolling envir...
Reviews
5.0
48 ratings
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Best Shooter on Gameboy?
What an unexpected release but absolutely enjoyable and appreciated release. After diving more into the platform and discovering more obscure games, a physical copy of ZAS became an easy "grail" piece for me, but I never thought it would be attainable given the price. If you are fan of classic shooters, you owe it to yourself to check this one out.
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Ricky · Today
Bing-Pow
Literally everything I ever wanted in a shooting game on GBC. Thank you Modretro for freeing this game from the over zealous hands of insanely high eBay auctions.
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Jeremy · May 27, 2026
Excellent Addition to the Modretro Lineup
To preface this, I've been on a shmup kick lately. Touhou, Twinkle Star Sprites on the Neo Geo, Mushihimesama, Pop'n TwinBee. Eclectic, mostly cute 'em ups, but no shortage of mechanical depth.
As part of my shmup conquest, S-11 seemed like an "easy" pick, so ZAS was the alternative I ultimately went with. Turns out that was the right call, ZAS offers the right amount of difficulty with some pretty interesting mechanical depth that sets it apart. On paper, it seems simple: one button fires, the other button switches between a concentrated shot and a spread shot. For the first stage, it seems like an either/or situation, one is clearly better than the other, et cetera.
A boss or two later? It starts setting in. Bullet patterns start facilitating the wider "spread" shot to create new angles, you're shooting around barricades to deal with problems you otherwise wouldn't be able to, you're neutralizing threats efficiently to foster your ongoing movement.
It's a Game Boy shmup, we're not dealing with Cave levels of danmaku. But for what it is? For a game that serves to cleanse my palate between bouts of Tetris and Traumatarium Penitent? This is an excellent shmup.