ECHO, a browser horror game played blind by sound

The full story

ECHO is a horror game you play blind: an implant turns sound into sight, so tapping your cane, stepping or throwing a stone shows the cave walls for a moment, and also tells the monster hunting you where you are. The poster didn't write the code; they described what they wanted, played it and complained, while Claude and GPT, running as coding agents, wrote and fixed around 15,000 lines of JavaScript on three.js. It has a wall-crawling spider with IK legs, a CRT bodycam shader, procedural cave materials, two chapters and touch controls.

For the trailer, Claude Code wrote a headless "director" in one session that freezes the game clock and steps it a sixtieth of a second at a time, rendering all 16 scripted shots in about three minutes. Instead of recording audio it logged every sound the game played and rebuilt the mix offline to match the frames, and it did the motion graphics in Python.