We posted the mystery image on Monday at 6:17 p.m. and on our social media accounts on Tuesday morning. Within minutes of appearing on social media, Yiannis had worked out the answer. The lesson we take from this: the Yanqi Basin puzzler was a bit too easy.
So we ask you: what should we do to make this more challenging? Do you have any suggestions for puzzler imagery? (Write to us directly, so as not to spoil the idea for the rest of the readers.) We will keep hunting for something that will stump you.