Red envelopes (ang pao, hongbao), Eid money and gift cards all arrive instantly, and digital versions in WeChat or GCash are just a tap. Nothing turns the gift itself into a private game. Here the lock is a riddle written from memories only two people share, so the money becomes a moment of being known, not just a transfer.
The data it runs on
Only what the sender types: 3 to 6 short shared memories, the recipient’s name, the occasion and the amount. No scraping, no contact access. The AI is also asked to check that each answer is not guessable from public social profiles (it reasons from the memory text alone, it does not search). Gap: if the sender gives vague memories, riddles get generic, so the app nudges for one concrete object, place, or nickname per memory. Fallback: a library of occasion riddle templates with a fill-in answer the sender writes by hand.
1. The mission
Make every gift of money feel like a letter. Families scattered across Manila, Toronto, Lagos and Dubai send money home all year. Riddle Envelope turns each one into a small game that proves you remember.
2. Why people can’t resist it
Being known. A riddle only you can solve says "I remember" louder than any amount.
The locked box. Money behind a puzzle is impossible to ignore. Curiosity plus reward.
The reply. Solving triggers a thank-you note and a memory swap, so families talk more, not less.
3. How it works for real
Login: email or phone, a passkey smart wallet is created behind the scenes (Coinbase Smart Wallet or Privy). No seed phrase. A paymaster sponsors gas on Base.
Fund: card, GCash, UPI, Pix or bank on-ramp to USDC on Base.
Write: a frontier LLM (Claude Sonnet or GPT via OpenRouter) turns memories into 3 riddle drafts with an answer, accepted variants and 3 escalating hints. A cheap model (Gemini Flash or DeepSeek) scores guessability and flags anything private or hurtful.
Lock: USDC goes into an escrow contract on Base keyed to the envelope. The answer is stored only as a salted hash. A 7-day timeout releases funds to the recipient automatically.
Judge: the recipient’s guess is normalised and checked against the hashed variants; a cheap LLM judges near misses ("tamagochi" vs "Tamagotchi") and returns warm or cold, never the answer.
Release: a correct answer calls the escrow, funds land in the recipient’s smart wallet, cash out to a local bank or e-wallet. x402 lets partner apps (greeting card shops, remittance apps) create envelopes per request.
4. Cost per use
Pennies per gift plus a tiny on-chain fee. Riddle drafts: about $0.01. Answer judging: under $0.001 per guess. Escrow lock and release on Base: about $0.002, sponsored.
Free: 3 envelopes a month, standard designs. Paid ($2.99 per month or 1% per envelope above 100 USDC): unlimited, premium animated designs, voice notes read by the recipient after unlock, family memory bank. Revenue also from on and off ramp partner share.
5. Growth loop
Every envelope reaches someone new. To open it they create a wallet with one tap. The thank-you note screen ends with "Send one back", and occasions repeat every year, so one family becomes ten. Between occasions, a Riddle Circle sends one small riddle a week between two people, keeps a running pair score and grows a deck of shared memories that makes the next big envelope better.
6. Risks and guardrails
Lost money: the 7-day fallback means a gift can never be stranded. Sender can also unlock manually.
Privacy: memories are stored encrypted, never shown publicly, and deletable. The riddle avoids health, addresses and passwords.
Scams: envelopes only come from known contacts; first-time senders show a warning; no envelope ever asks the recipient to pay.
Compliance: licensed on and off ramp partners handle KYC; amounts above local thresholds require verification.
7. MVP build order
Email login with smart wallet on Base Sepolia; escrow contract with answer hash and 7-day timeout.
Memory form and riddle drafting prompt with hints and accepted variants.