https://store.steampowered.com/app/4709930/Harmonic_Drive/

Harmonic Drive is an arcade-style rhythm game centered around reactive visuals, customizable charts, community-created content, multiplayer, score chasing, and electronic music.

The source code is open so developers, rhythm-game players, modders, artists, and other contributors can help shape where Harmonic Drive goes next.

Want to just play the game? The easiest way to play Harmonic Drive and support continued development is to purchase the official Steam release for $1.99 or checkout the Apple native version via the App Store on iOS & macOS.

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🎵 What is Harmonic Drive?

Harmonic Drive combines traditional lane-based rhythm gameplay with highly reactive visual effects and extensive player customization.

Instead of treating the background as a passive visualizer, Harmonic Drive’s Emotional Motion System (EMS) allows charts and creators to control the visual presentation of a song alongside its notes.

The game supports both built-in content and community-created charts through the Steam Workshop.

Whether you want to chase leaderboard scores, create charts, experiment with EMS effects, play with friends, or contribute code, Harmonic Drive is designed to be expanded.

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✨ Features

Rhythm Gameplay

• 4-key through 8-key chart support
• Multiple difficulty levels
• Multiple gameplay modes
• Customizable note speeds and gameplay settings
• Input calibration for low-latency play
• Score and combo systems
• Online leaderboards
• Steam achievements
• Gameplay modifiers and unlockable loadouts

Emotional Motion System (EMS)

Harmonic Drive includes its own visual effects system called the Emotional Motion System.

EMS allows songs and charts to control visual elements alongside the music, creating a presentation that reacts directly to the chart.

The included EMS Creator allows creators to build and customize their own effect configurations.

Chart Editor

Create your own playable charts directly within Harmonic Drive.

The chart system supports:

• 4KEY–8KEY layouts
• Multiple difficulties
• Custom audio
• Community-created charts
• EMS integration
• Chart importing and sharing

Steam Workshop

The official Steam edition includes Workshop integration for community content, including:

• Custom charts
• EMS packs
• Community-created content

Multiplayer

Harmonic Drive includes online multiplayer and cross-platform multiplayer functionality.

Community Development

Harmonic Drive is no longer intended to be developed by only one person.

The community is invited to help build it.

That can mean:

• Fixing bugs
• Improving performance
• Improving UI/UX
• Creating new gameplay modes
• Improving existing gameplay
• Expanding the chart editor
• Adding accessibility features
• Improving controller support
• Creating new EMS effects
• Improving multiplayer
• Adding customization
• Improving Linux/macOS/Windows support
• Writing documentation
• Creating tests
• Suggesting new features

You don’t need to redesign the entire game to contribute.

Small improvements are welcome.

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🚀 Official Steam Version

Harmonic Drive is available on Steam for $1.99.

Purchasing the Steam version is the easiest way to play Harmonic Drive and directly supports continued development.

The official Steam distribution provides a ready-to-play build along with Steam-specific integration such as:

• Automatic installation
• Automatic updates
• Steam Workshop
• Steam achievements
• Steam Cloud
• Steam leaderboards
• Multiplayer integration

If you aren’t interested in compiling a Godot project yourself, the Steam version is the recommended way to play.

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🛠️ Building From Source

Harmonic Drive is built using the Godot Engine.

Requirements

You will need:

• Git
• Godot 4.6
• A supported desktop operating system
• The dependencies required by the project

Clone the repository:

git clone git@github.com:KareelHicks/HarmonicDriveSteam.git cd HarmonicDriveSteam

Then open the project in the appropriate version of Godot.

Note: Some proprietary, licensed, platform-specific, or redistributable-at-runtime components may not be included in the source repository.

Additional setup instructions will be documented as the open-source build process is finalized.

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🤝 Contributing

Contributions are welcome.

Harmonic Drive is being opened specifically because I want other developers and players to have the opportunity to improve the game.

If something bothers you, fix it.

If you have an idea for a game mode, prototype it.

If you think part of the UI could be better, improve it.

If you’re a rhythm-game expert and think a gameplay system could feel better, I especially want to hear from you.

A typical contribution workflow is:

1. Fork the repository.
2. Create a branch for your change.
3. Make and test your changes.
4. Commit your work.
5. Push your branch.
6. Open a Pull Request.
7. Explain what you changed and why.

Example:

git checkout -b feature/my-awesome-feature

Then:

git add . git commit -m "feat: add my awesome feature" git push origin feature/my-awesome-feature

Open a Pull Request against the main Harmonic Drive repository.

Please keep Pull Requests focused when possible. Smaller, well-tested changes are generally easier to review and merge.

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💡 Feature Ideas

Not sure where to start?

Potential contribution areas include:

• New rhythm gameplay modes
• New modifiers
• New EMS effects
• Chart Editor improvements
• Better chart creation workflows
• Improved multiplayer
• Multiplayer game modes
• Better controller support
• Steam Deck improvements
• Performance optimization
• UI/UX improvements
• Accessibility
• Additional customization
• Better onboarding/tutorials
• Linux compatibility improvements
• macOS improvements
• New visualizers
• Practice tools
• Community features

Check the repository’s Issues for bugs, planned features, and contribution opportunities.

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🐛 Bugs and Feature Requests

Found a bug?

Have an idea?

Please create a GitHub Issue.

When reporting a bug, include as much information as possible:

• Operating system
• Hardware, when relevant
• Harmonic Drive version/commit
• Steps to reproduce
• Expected behavior
• Actual behavior
• Screenshots/video when useful
• Relevant logs or error messages

Good bug reports make fixes significantly easier.

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🎼 Music and Game Assets

The source-code license does not automatically grant rights to all music, artwork, branding, third-party assets, or other content associated with Harmonic Drive.

Some assets may have separate licenses or redistribution restrictions.

Unless explicitly stated otherwise, do not assume that music, third-party assets, Harmonic Drive branding, or other separately licensed content may be redistributed simply because the game’s source code is publicly available.

The official Harmonic Drive soundtrack includes music by DJ Iatneh, with AI-assisted music generation disclosed on the Steam store.

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⚠️ Steamworks

The public source repository may differ from the official Steam production build where necessary for Steamworks, credentials, signing keys, backend services, proprietary dependencies, or other platform-specific integrations.

Never commit API keys, passwords, signing keys, certificates, access tokens, or other secrets in a Pull Request.

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🔐 Security

If you discover a security vulnerability, authentication issue, exposed credential, exploit, or other security-sensitive problem, do not publish sensitive details in a public GitHub Issue.

Please report security-sensitive problems privately to the project maintainer.

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📜 License

Harmonic Drive’s open-source code is licensed under the Apache License 2.0.

See LICENSE for the complete license terms.

Third-party libraries, music, artwork, fonts, SDKs, and other assets may be subject to their own licenses.

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❤️ Support Harmonic Drive

There are several ways you can help the project:

• Buy Harmonic Drive on Steam
• Star this repository
• Report bugs
• Suggest features
• Submit Pull Requests
• Create charts
• Create EMS packs
• Participate in the Steam Workshop
• Tell other rhythm-game players about Harmonic Drive
• Help improve the documentation

Harmonic Drive on Steam — $1.99

Every purchase and contribution helps justify continued development.

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👨‍💻 Developer

Harmonic Drive

Created by Kareel Hicks

Published by Emotive Studios LLC

Originally released on Steam on June 3, 2026.

Harmonic Drive is now being developed with the goal of becoming a community-driven rhythm game where players and developers can directly help determine what the game becomes.

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Thank You

If you’re looking through this repository because you’re interested in Harmonic Drive, rhythm games, Godot development, or open-source game development:

Thank you for being here.

This project started as a solo-developed game.

The next version doesn’t have to be built alone.