I built ProofOfSolve (https://proofofsolve.com), a Bitcoin puzzle hunt solved entirely on Google Street View.

How it works
- Each puzzle has 12 clues. Each clue leads to a spot on Street View that hides one word.
- The 12 words, in order, are a BIP39 seed. The first correct answer submitted on the site wins.
- The wallet also has a passphrase, which goes to the winner. Finding the 12 words alone can't sweep it, so nobody can front-run the solver.
- 3 tries per 24 hours, so brute force goes nowhere.

The first three open Saturday, Oct 24 at 6:00 AM Central (11:00 UTC):
1. Meridian, Mississippi (free): bc1qphjz3cxsj8ls498uker4l703cqpg3fqx2g8tza
2. George Washington's Mount Vernon (free): bc1qqs2f7a3n6p3s694kh8rvcyccnf4n5n733nc0ut
3. Alcatraz Island ($10 entry): bc1q6830c0qx9975llvq8a0q0urmaxpa6yhgtgusx4
Each holds about $125 right now. Check them on any explorer.

Provably fair: the answer fingerprint for each puzzle, SHA-256(salt + answer), is published now on the site and on GitHub (https://github.com/ProofOfSolve/puzzles), dated before launch. After each solve, the answer and salt are revealed so anyone can verify it never changed, and the payout is on-chain.

Clues stay hidden until launch. Questions and feedback welcome.