Inspiration
The inspiration for Ghost Runner came from a staggering reality of modern life: the sedentary epidemic. In 2026, the average adult spends over 9 hours a day sitting—a habit that has become as harmful to cardiovascular health as smoking. We realized that for students and office workers, the "lonely jog" or a walk around the block feels like a chore because it lacks the immediate feedback and dopamine hits of the digital world.
We wanted to create an "escape hatch" from the chair. By blending the addictive mechanics of gaming with the physical necessity of movement, we sought to turn the mundane act of standing up and running into a high-stakes, cinematic quest where you aren't just a user—you’re the hero.
What it does
Ghost Runner is an immersive, eyes-free AR fitness experience designed to break the cycle of sitting. It uses spatial audio and real-time GPS to turn your environment into a competitive arena.
The "Creep" Mechanic: The app projects a "Digital Ghost" (your past PR or a friend's record) into your 360-degree soundstage. As the Ghost closes the gap, you’ll hear rhythmic footsteps and heavy breathing getting louder and closer in 3D space.
Psychological Pacing: If the Ghost gets within 2 meters, a pulsing heartbeat triggers in your ears, activating your natural "fight-or-flight" response to push you through the fatigue.
Hands-Free HUD: While it features a beautiful neon radar for selecting "Ghosts" and viewing 3D Mapbox routes, the experience is designed to be fully auditory, allowing you to focus on the terrain, not your phone.
Victory Soundscapes: Crossing the finish line ahead of your Ghost rewards you with an immersive, spatial crowd cheer, providing the instant gratification that traditional fitness tracking lacks.
How we built it
React Native (Expo) for the mobile app Firebase Authentication for login/signup Cloud Firestore for data storage (users, runs, friends) Expo Location + Maps for GPS tracking Expo AV + Haptics for audio feedback React Navigation for app navigation
Challenges we ran into
GPS Jitter: Standard GPS data is noisy, often making the Ghost "teleport" or jump around. We had to implement a Kalman Filter to smooth the path data for a realistic audio experience.
Audio Latency: Delivering real-time 3D sound that responds to micro-changes in position was a hurdle. We had to optimize our React Native bridge to ensure the footsteps didn't "lag" behind the GPS updates.
Battery Efficiency: Running high-frequency GPS, 3D mapping, and spatial audio simultaneously is a massive drain. we optimized the background processing to ensure the app could survive long-distance runs.
Accomplishments that we're proud of
We are incredibly proud of creating a "Heads-Up" AR experience that doesn't require glasses or a screen. Successfully mapping a digital coordinate to a physical sound that "creeps up" behind a user was a massive technical win. We've managed to turn the most boring part of a healthy lifestyle into something that feels like a scene from a thriller movie.
What we learned
We learned that sound is a more powerful motivator than sight for high-intensity activity. Designing for "Audio UX" taught us how to use volume and panning to communicate complex data (like distance and speed) without words. We also gained deep experience in geospatial math and the intricacies of mobile sensor fusion.
What's next for Ghost Runner
Social "Territory War": A map-based mode where students can "claim" areas of campus by outrunning the local "Ghost" of that zone.
Haptic Feedback: Integrating watch haptics to "nudge" the user when the Ghost is about to pass them.
Smart "Sedentary" Alerts: Connecting to desktop activity to trigger a "Ghost Chase" the moment the app detects you’ve been sitting for over 60 minutes.
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