I Built an On-Device "Solstice Engine" Using TensorFlow.js to Break Ciphers

A developer built an on-device 'Solstice Engine' using TensorFlow.js to break ciphers in a browser-based puzzle game. The game, Solstice Cipher, uses real-world light levels detected via webcam to alter cryptographic logic, requiring players to physically change lighting conditions to decode messages. The project is open-source and runs entirely client-side with no backend servers.

This is a submission for the June Solstice Game Jam I wanted to build something that forces the player to look around their room, grab a flashlight, or turn on the light, and interact with the physical world Solstice Cipher is an atmospheric, browser-based puzzle game inspired by Alan Turing’s legendary code-breaking machines and the beautiful transitions of the June Solstice. The game challenges players to step into the shoes of a wartime cryptanalyst to intercept and decode three hidden binary messages celebrating June milestones. Just like the solstice marks a shifting point between light and darkness, this machine’s cryptographic system alters its logic based on the actual, real-world light in your room . To fully break a cipher, you have to decipher cryptic riddles and physically shift your environment between Day Mode shining a light at your webcam and Night Mode covering the lens to calibrate both mechanical rotors Take a look at the "Solstice Engine" in action The entire project is completely open-source, free, and lightweight built using HTML, CSS, and client-side JavaScript . You can explore the repository or host your own version below: Building this was an absolute joy and a fun logic puzzle in its own right I wanted to ensure the game was 100% free to run, private for the player, and required zero backend servers or complicated API keys. navigator.mediaDevices.getUserMedia , the app securely requests access to a localized 320x240 video matrix. app.js to feature persistent memory flags dayCalibrated and nightCalibrated . Now, the engine securely holds its state when you successfully align a rotor, politely guiding you to switch from flashlight to shadow to finish the job. style.css to create that clandestine, high-stakes "secret bunker" aesthetic.This game is an ode to the father of modern computing. Instead of a standard clicker game, the mechanics intentionally simulate the interactive physical dial-tuning of the Enigma-decrypting Bombe machines. The puzzles themselves lean heavily on binary data arrays and computational logic definitions, and the initial level unlocks a direct tribute to Turing's profound impact as both a computer science pioneer and a June Pride icon. To drive the core mechanic without adding any friction or registration steps for players, I utilized Google TensorFlow.js loaded straight from a CDN. Inside app.js , every frame from the user's webcam is treated as an active mathematical playground. The application converts frame pixels directly into data streams on the browser GPU using tf.browser.fromPixels . By using localized matrix mathematics with tf.mean , it reads the average brightness value instantly. This turns a simple consumer webcam into a zero-latency, private, on-device environmental sensor It shows off just how incredibly accessible, lightweight, and versatile Google's open-source AI ecosystem can be. Thank you so much for hosting this jam Getting to use history, AI, and creative web design to celebrate a beautiful month of milestones was an incredibly rewarding experience. Good luck to everyone participating