> Does such a mechanism exist? Sign the puzzle solution with your private key. Check signature inside the circuit. This obviously can't be applied to this part

> Does such a mechanism exist? Sign the puzzle solution with your private key. Check signature inside the circuit. This obviously can't be applied to this particular game since it has a circuit that does not employ such measures. Alternatively, if used snark is recursive - create a new circuit that will both validate original proof and check the signature.