In the game the player takes the role of a flying creature that flies through a series of side-scrolling levels and is equipped with a ball that can fire in eight directions. Each of the different directions of the D-Pad corresponds to a different music note and the ball flies quantized to the music, making for a game where the player creates the background music as they play. Even though the ball is the method of attack against enemies, its main use is to collect flying music notes. Collecting notes fills up a music meter at the bottom that warps the player to the stage boss once it's filled.
Playing a few levels unlocks B.G.M. Mode where the player can fly through every stage endlessly and simply create music, along with a Music Creator to allow the player to create and edit their own soundtracks.
Because the game made special use of the Famicom Disk System's extra sound channel, it never released outside Japan.
Tropes:
- Attack of the 50-Foot Whatever: The end stage bosses are all giant music notes.
- Endless Game: B.G.M. Mode allows the player to fly endlessly through a level and freely compose music.
- Musical Gameplay: The game revolves around using your multi-directional projectile to produce music.
- Sequel Hook: The game's credits tell the player that the game will continue in Octocky 2.
- Tech-Demo Game: The game was made specifically to use the Famicom Disk System's extra sound channel, producing music that the Famicom and American NES could not possibly produce.
