VoltRhythmVoltRhythm

VoltRhythm is a retro-futuristic four-key rhythm game where rhythm play generates power. Accurate rhythm play emits a large amount of "rhythm energy," which can be converted to usable electricity with surprising efficiency. Your goal is to fill the energy reserves by playing as many songs as possible with as much accuracy as possible.

Though, what is the reason for gathering this much energy...?