Should we have a specific close-vote option for "don't ask us to do challenges from games for you"?
No, because we already have it.
Requests for analyzing ciphertext or reviewing full cryptographic designs are off-topic, as the results are rarely useful to anyone else and/or would be too long for this site.
These challenges would fall under "request for analyzing ciphertext" most of time.
If they don't and they would make for a good question, ie one about cryptographic schemes, I don't see a reason why we would want to close them.