The Electroplankton universe (エレクトロプランクトン, Electroplankton) is one of the many unique universes represented in Super Smash Bros. Brawl. The universe consists of only a single title (excluding the DSiWare re-release, split up as the game's 10 stages for individual sale): a relatively obscure music creation software. Its only representation is a stage, Hanenbow, and a few stickers.
Hanenbow: Hanenbow is a secret stage in Brawl representing the Electroplankton universe. It is unlocked by finishing Event 28: Flower Blooms in the Echoes. Hanenbow is the only stage where My Music does not work; the music is generated by the actions of the players and the Hanenbow that fly around the stage. The leaves change color and angle when struck.