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.
Electroplankton is one of two universes to be completely cut from Smash Bros. The other is Metal Gear.