Most levels are 3–5 minutes, ideal for commuting.

For the uninitiated, Project Arrhythmia defies easy categorization. It is a minimalist rhythm game where players control a small geometric ship (usually a square or triangle) and must dodge incoming "notes" that are synchronized to a beat. Instead of tapping to the rhythm, you are surviving to it. Every bass kick, synth chord, and drum fill manifests as a projectile, a laser, or a shifting wall.

The file wasn’t supposed to exist on the store. It had no developer name, no screenshots, and the description was just a string of binary that translated to “HEARTBEAT DETECTED.” It was simply called Arrhythmia.apk .