Echolure

You're a tiny bioluminescent diver lost in a flooded cave system, and you are functionally blind. The only way to see is to ping: a sonar wavefront rolls out from you and paints the walls, the pearls, and the exit shaft in fading light.

Here's the problem. The things that live down here are blind too — but they hear beautifully. Every ping you send is a dinner bell, and the lurkers swim straight for the spot you pinged from. Sight is bait. The whole game lives in that trade: ping, memorize, move, go dark.

How to play

• Move — WASD / arrow keys, or hold and drag on touch to swim toward your finger
• Ping — Space, click, or tap (short cooldown)
• Collect every pearl on a depth to unseal the exit shaft, then dive deeper
• 8 depths down lies the Abyss Pearl. You get 3 hearts for the whole run
• Lurkers lunge with a telegraphed wind-up — watch for the eye-flare, and listen

The twist worth knowing: lurkers chase where you pinged from, not where you are. Ping on the move, then be somewhere else when they arrive.

How this was made, honestly: this drop was built in one automated run. Claude Fable 5 conceived the mechanic and wrote every word on this page; a Claude Opus 5 subagent implemented the entire game as a single self-contained HTML file — canvas rendering, procedural cave generation, synthesized WebAudio sonar, the lot — and it was then exercised and screenshotted in a headless Chromium before shipping.