Following the release of Donkey Kong Country: Tropical Freeze, Retro Studios began work on an original, music-themed 3D platformer titled Harmony, initially starting development as a Wii U title before being moved over to the Nintendo Switch. The game was ultimately cancelled in 2017 on Nintendo's orders following years of stagnant development, after which Retro Studios shifted focus to the Nintendo Switch port of Tropical Freeze and Metroid Prime Remastered before being assigned to develop Metroid Prime 4: Beyond.

In April 2025, development materials from Harmony were leaked as part of a dump from a Nintendo Switch developers' kit. The builds containing these assets cover three distinct phases of development, stretching all the way to just before the game's cancellation. Various features introduced in Harmony's game engine would later be carried over to Metroid Prime Remastered in 2023.