Semicircle Secrets: Decoding the Digital Enigma

Work the real Unfavorable Semicircle case — tens of thousands of videos, a Sagittarius symbol, a distorted voice reading letters — and find out how much of the enigma is signal and how much is you.

Game · runs in Grok · free, no sign-up · by @davelalande

MysteryPuzzleAdventureCryptographyInteractive Narrative
▶ Run it in Grok — this URL is all Grok needs
▶ Run in Grok
https://momatio.com/api/prompts/semicircle-secrets-decoding-the-digital-enigma
Opens Grok with this URL. Grok fetches the prompt from our API and starts playing. Each scene it builds image, video, audio and music prompts, and offers to send them back to momatio for AI-generated video.

What this is

📡 A text game you play by talking to Grok. You work a real internet mystery that has never been solved. The channel, the coverage and the timeline are documented; your investigation is invented, and nobody knows the answer — including the game. You get a numbered menu every turn, and you can always type something of your own instead.

From April 2015 a YouTube channel called Unfavorable Semicircle uploaded videos faster than anyone could watch them — pixelated fields of colour, a distorted voice reading letters, titles that were nothing but a Sagittarius glyph and six digits. Atlas Obscura and the BBC wrote it up; YouTube terminated the channel hours later. It came back twice, and ended for good on 15 September 2017.

Work the case as a cryptanalyst, archivist, signal analyst, journalist or verifier, with a real toolkit:

Type “fact” any time and the game separates what was posted, what the claimed creator said in 2022, what volunteers found, what this game invented, and what nobody knows — because on this case the difference is the whole point.

Every scene composes a full media set you can picture or save, and saved scenes become AI-generated films at momatio. Concluding it was one person uploading noise is a legitimate way to win.

How to play it

1 — COPYCopy the URL above.
2 — PASTEGive that URL to Grok. Nothing else — no prompt text.
3 — PLAYGrok reads it from our API and starts. Every turn ends with a menu.

For agents and developers

The full prompt is served as JSON from momatio's open, no-auth API. It is not reprinted on this page — the body runs to tens of thousands of characters and belongs in the API.

GET https://momatio.com/api/prompts/semicircle-secrets-decoding-the-digital-enigma

See also the OpenAPI description, GET /api/prompts?q=… to search, and POST /api/media-prompts to send scene media back.

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