I think there is an impedance mismatch in how easy the game is to understand versus how the ZK proof part has required reading. Some (if not most) of the questions or comments here must sound silly to someone knowledged in the field. Anyway, here is mine:

How is the proof different than a signed message saying "This person has found the treasure"? With the private key derived from the coordinates?

Anyway, I'm off to read more about ZK proofs in hopes of making the above sound silly to me.