DuoChart

---

Overview

DuoChart is a rhythm game designed for Apple devices. Notes travel down a five-lane highway in time with the music and are played as they reach the frets. When a song includes a music video, it plays behind the highway; when it includes lyrics, they are shown line by line as the song plays.

DuoChart is free. It is not available on the App Store and is distributed here for self-signed installation.

Songs

DuoChart plays standard rhythm game song folders: a .chart or .mid file with the song's audio, and optionally album art and a video. Existing song libraries from other rhythm games work without changes. No songs are included.

iPhone: open Songs, tap Import, and choose one or more song folders in Files. Folders can also be copied to On My iPhone › DuoChart › Songs.

Mac: choose a songs folder in Settings.

Installation

Because DuoChart is not distributed through the App Store, each copy is signed by the person installing it.

iPhone

1. Download DuoChart-iPhone.ipa from the latest release.
2. Install it with a sideloading app such as AltStore, SideStore or Sideloadly, signed with your own Apple Account.
3. If iOS asks, turn on Developer Mode in Settings › Privacy & Security, and trust your Apple Account in Settings › General › VPN & Device Management.

Apps signed with a free Apple Account expire after seven days. Refresh DuoChart in the sideloading app to continue playing; songs and scores are kept.

Mac

1. Download DuoChart-Mac.zip from the latest release and open it.
2. Move DuoChart to your Applications folder.
3. On first launch, Control-click DuoChart and choose Open, then Open again. If macOS still blocks it, go to System Settings › Privacy & Security and choose Open Anyway.

Details

Requirements	iOS 26 or later on iPhone. macOS 26 or later on Mac.
Controls	The on-screen fretboard on iPhone. D F J K L on a Mac keyboard, with keys that can be reassigned.
Calibration	On iPhone, a one-time calibration in Settings times every song to the device and audio setup.
Chart editor	On Mac, charts can be written for any song by playing along at reduced speed.
Scores	Best scores are kept on the device. On iPhone, each run is checked note by note against the chart before it is posted to that song's leaderboard.
Game Center	Not available in self-signed copies.
Source code	Not published.

About

DuoChart is developed by Deoxy Labs, an independent software company based in New South Wales, Australia and Texas, USA. Questions and problem reports can be filed as issues.

Song charts, audio and videos remain the property of their respective owners. DuoChart does not include or distribute music.