How I built a supersonic AI riddling duel in under 20 Minutes (with zero manual coding)

Can an AI developer agent build complex full-stack logic without constant hand-holding?

To test this, I set up the #NapkinChallenge: take a rough architectural sketch on a paper napkin and turn it into a fully functional web application in under 20 minutes.

The goal: Build "Blaine the Mono's Riddling Competition" — a game where you duel a psychotic, sentient supersonic monorail from Stephen King's The Dark Tower series. If you trip him up with three logic-defying riddles, you save the passengers. If his neural net solves them, you crash at Mach 4.

The result? The AI built the entire application with zero manual lines of code written by me.

Here is how the architecture works, how the backend uses the new @google/genai SDK, and how you can run the challenge yourself.