Do I understand correctly that someone solved this puzzle and took a prize for themselves? If so, how long did it take to solve the puzzle?
To understand this "puzzle", you need to go to page 1. Then read this:
https://bitcointalk.org/index.php?topic=5166284.60You can see mining doing similar activities to get rewards. Here you are provided with information regarding the pieces that make up the key to open the gold chest that is hidden.
Many people have opened their gold chests and earned a large sum of money from it. However, this is very difficult, and it is harder than what you are thinking.