[Hackathon Blog] I Joined Builders Weekend 2026 in Tokyo

Group Photo!!

From March 20th to 22nd, I joined Builders Weekend 2026, a 48-hour hackathon in Tokyo. It was an incredible experience. I want to share my experience.

Builders Weekend 2026 · Luma

About the Hackathon & Atmosphere

The event was at Shibuya PARCO Building 18F in Tokyo. It was organized by Digital Garage, with sponsors including Lovable, VoiceOS (YC X25), Supercell, RevenueCat, ElevenLabs, and Open Network Lab.

The judges were Yoshi Ueda (RevenueCat), Kai Brokering (VoiceOS), Mitsumasa Kiyohara (Open Network Lab), and Jerry Chi (Supercell AI Lab). The theme was: “Build cutting-edge AI products in 48 hours.”

Sponsored Companies!! Special Thanks!!

I teamed up with Tatsuki Akiyoshi(LinkedIn). Both of our names start with “T”, so we named our team “T squared”.

Our Project

We created “SkyForce” — a 3D aerial combat game controlled entirely with AirPods. No screen touch needed.

Please watch this demo movie.

Playing video

How to play:

• Move your head → Steer the jet (AirPods gyro)
• 1-tap AirPods → Fire missile
• 2-tap AirPods → Talk to AI commander
• Look up → Boost
• Headbang → Special weapon

We also implemented an in-app purchase system with RevenueCat and a landing page with Lovable.

The store page in this app and the landing page on the web

You can visit our landing page

Technical Highlights

The app is a native iOS game built with Swift, SwiftUI, and RealityKit. It includes an AI commander (Claude API + ElevenLabs), AI enemies (Claude API), and an in-app purchase system (RevenueCat).

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The landing page is built with Lovable and includes an original movie made with Remotion.

By using Claude on Chrome MCP and my custom MCP server for autonomous iOS E2E testing, I was able to work on multiple tasks in parallel. This allowed me to develop a lot of features in a short time.

I also used the AirPods gyro sensor and audio playback commands to control the app without touching the phone, achieving low-latency hands-free operation.

The Pitch Time

Tatsuki did the pitch for our team. He also prepared the demo video, the pitch script, the base of the landing page and more. I was able to focus on development thanks to Tatsuki. I really appreciate his work!

Tatsuki did the pitch on the stage

The Prizes

Fortunately, we won two prizes: the VoiceOS Prize and the RevenueCat Prize. We were truly happy to receive them!

​We took a photo with Kai Brokering (VoiceOS)

​We took a photo with Yoshi Ueda (RevenueCat)

Finally

I want to thank everyone who found our product interesting. It made the 48 hours of hard work feel worth it.

I tried to combine hardware sensors, AI, and game development in a new way. I learned that AirPods — something millions of people already own — could become a game controller. There are almost zero games on the App Store that use AirPods gyro as input, so this feels like a new category.

My biggest lesson: by using AI for parallel development and letting AI handle the creative production work, I could build a complex app in 48 hours while focusing on decisions and quality.

Huge thanks to my teammate Tatsuki, the organizers, Digital Garage, and all the sponsors for making this event possible!

Thank you for reading!