The Metronomicon: Slay The Dance Floor

Packing in a fully-fledged story mode with a colourful cast of musically-empowered heroes and villains, The Metronomicon sees you take control a party of eight newly graduated masters of the "rhythmic combat arts" to wage musical warfare against a multitude of dance-mongering fiends. By switching between four concurrent hero-controlled tracks on-the-fly, you'll select and activate a wide array of abilities and spells, buffs and nukes, with your performance and timing all-important in ensuring the effectiveness of your moves.
In the RPG spirit, you'll need to improve your characters' stats, hunt down powerful equipment, and combine a multitude of newly-learned abilities - switching between tanking, healing, buffing, and damage-dealing classes as required in real time.