The player must reach the end of each stage and defeat the boss, while avoiding hazards scattered across the map such as enemy mechs and gun turrets.

The initial ideas for Bangai-O came from Treasure programmer Mitsuru Yaida who wanted to challenge himself by programming an extreme number of bullets on the screen at once.

The team replaced most of the graphics and audio, changed some gameplay elements, and re-released it on the Dreamcast three months later, a version later released internationally.

The story follows Riki and Mami in their efforts to stop criminals from smuggling fruit contraband to finance their evil deeds.

The two pilots can be interchanged instantaneously, Riki fires homing missiles and Mami shoots reflecting projectiles which bounce off walls.

In the Dreamcast version, the bullets are stronger, and destroying objects and enemies refills the bomb attack meter instead of fruit which now only add to the player's score.

[1][8][9][10] Yaiman began thinking about the programming challenges involved in detecting when the bullets collide with other objects, and started work on a prototype.

He later received permission from company president Masato Maegawa to pull in other staff and work towards producing a full game.

[20] At the Electronic Entertainment Expo (E3) in May that year, IGN reported that a company had begun localizing the game, and had given it English menus and renamed it Bangai-O from its obscure Japanese title, Bakuretsu Muteki Bangaioh.

[a][21] In December, industry newcomer Conspiracy Entertainment announced they were localizing Bangai-O along with another Dreamcast game, Record of Lodoss War (2000).

[2][17][31][32] Eric Mylonas of GameFan called it a mix between the free-floating gameplay of Sub-Terrania (1994) and the rotating shooting action of Omega Boost (1999).

[31] Rick Mears (GameFan) wrote that it felt like Robotron (1982) with its unique control style, and called it an "old school 2D treat".

[2][32] Gantayat pointed out the scatter bomb attack that fills the screen with bullets "a momentous occasion...one of the main parts of the Bangai-O experience".

[6][26][34][36][39] Gantayat (IGN) and Matt van Stone (GameFan) preferred this new version because of the updated graphics, new CD-quality soundtrack, and more streamlined gameplay.

[3][6] With this release, journalists were more critical of the graphics and audio, commenting more heavily on the game's appeal primarily as a nostalgic shooter.

[38] Human Tornado of GamePro said, "This well-designed 2D shooter will satisfy fans of old-school arcade ation games, but Bangai-O doesn't break any new ground.

"[40][d] Despite never having been reviewed, the Dreamcast version was nominated at The Electric Playground's 2001 Blister Awards for "Best Console Shooter Game", but lost to Halo: Combat Evolved.