What is codex-usage-game?

FAULTLINE, subtitled Ride the Echo, is a tiny arcade style game that hides inside what looks like a Codex usage chart. It is playable directly in a browser, and the whole idea started as a joke about how a usage graph on a screen could double as a game board. The concept is simple. You ride along living contour lines on the chart, dodging broken signals as you go and collecting echoes along the way. When you get boxed in with nowhere left to move, you can use a phase pulse to slip through danger instead of getting stuck. The goal is to survive for sixty seconds, at which point the transmission is considered restored and you have won the round. Controls are kept minimal so anyone can pick it up immediately. You move between the contour lines using the up and down arrow keys or the W and S keys, and you press space or tap the screen to phase through danger. You can also drag to choose which contour line to move onto. The project credits its idea to an original social media post from a user named thsottiaux, who shared a screenshot of a real Codex usage chart that sparked the idea of turning it into a playable game. The README includes that original chart image side by side with the finished game concept. Notably, the entire game was designed, built, and polished by an AI system called GPT-5.6-Sol-Ultra in about 30 minutes, starting only from that screenshot, with a person then publishing the result. The project is small, written in HTML, and released under the MIT license, so anyone can view, copy, or build on it freely.