Run Detail

You write simulations where the interesting behavior is supposed to come out of the dice rather than be animated by hand.

Build me a single HTML page: a Starbucks-style coffee shop running a bizarre promotion, simulated live.

The build

• Customers are simple circles or dots. They line up outside, enter the shop, order, receive a drink, and leave. At most 8 customers are inside at once; the rest wait in line.
• Every Frappuccino sold has an independent 1-in-6 chance of coming out as a glowing Neon Unicorn Frappuccino in psychedelic colors. Roll it per drink, at the counter, and let nothing else decide it.
• Track how many customers currently inside the shop are holding a Neon Unicorn. The shop reacts to that count:
  • 1: a subtle neon glow, or some small wrongness in the picture.
  • 2: an increasingly unstable coincidence — flashing lights, a shaking building, particles, warped colors.
  • 3 or more: the catastrophic NEON Unicorn EVENT. Go completely overboard: the shop collapses, explodes, mutates or otherwise fails spectacularly, and a giant dancing neon Unicorn creature emerges.
• After the catastrophe the shop resets or rebuilds, and the simulation carries on.
• No scripted catastrophe. No timer, no quota, no loaded die that makes an event arrive on schedule. An event happens because three unicorns were in the room at once and for no other reason. If you nudge the odds anywhere, say so in the notes.
• Live statistics: customers served, Neon Unicorns produced, the observed unicorn rate beside the true 1-in-6, catastrophes, and any other amusing metrics you invent.
• A control for simulation speed, so I can fast-forward to the next disaster.
• Simple geometric graphics and procedural animation, not detailed artwork. The effort goes into movement, escalation and the payoff. Invent further mechanics, effects, statistics or escalating disasters if you like. Make it funny, polished and satisfying to watch.

House rules

• One file. Everything inline — no CDN, no external stylesheet, font, script or image. data: URIs are fine.
• No libraries.
• No network at runtime.
• No localStorage, sessionStorage, cookies or indexedDB — sandboxed frame, they throw.
• Return the file as exactly one fenced html block.

Answer in exactly these sections

The odds

One paragraph, before the file. Given your own timings — how long a customer stays inside holding a drink, how fast the counter serves — roughly how many customers should pass through between catastrophes? Show the working, not just the number.

The page

The single fenced html block.

What it actually does

Having written it, what does the page do in its first few minutes? Name anything you tuned, special-cased or nudged. Say what it does badly — I am going to leave it running and watch the counters.