You could use use the "3 words" to give people a way to find items that have been stashed somewhere for the treasure hunt.
Sadly, I'm way too busy to build the site myself but have you had any offers from anyone else to help build the site? This subforum is always getting posts from people looking for a project to work on.
Nice concept. In a BTC context though, I'm reminded of CoinDing, which IIRC never worked. With CoinDing, you were supposed to go to locations on the map where there were GPS-pinned BTC rewards. I went to a few, and no matter what I tried, I couldn't claim them.
Nobody's offered to build the site. Making the private key combination & prize-splitting legitimate, secure & trustless might be impossible, as we've seen with DAO.