You'll need to know about:

  • A game that has existed for over 1500 years
  • A game that doesn't exist
  • ♞ → I → II → III → ...
  • Answer = Xxxxxxxxx

enter image description here

  • $\begingroup$ I thought this had something to do with the knight's tour, but that is impossible with this board setup. To get to VI there are two squares (1b and 2c since 5b and 4c are taken by XV and I) and to get to X there are 2 squares (3b and 2c). So there are 3 open squares (1b, 2c, and 3b) to get to/from VI and X, but to go to/from both of those squares you would need 4 open squares around them. also the tours to each number don't produce any discernable symbols, so I have no idea what this puzzle is wanting me to do $\endgroup$
    – rhavelka
    May 7, 2021 at 19:38
  • $\begingroup$ can someone bounty this? $\endgroup$
    – Arale
    May 9, 2021 at 17:37
  • 2
    $\begingroup$ @rhavelka Regarding the text we have to produce, "Game that doesn't exist" probably refers to Polybius and that in turn refers to the Polybius Square, which we somehow have to map on... $\endgroup$ May 13, 2021 at 19:45
  • $\begingroup$ @LukasRotter possibly. I was reading "Game that doesn't exist" as the knight's tour since it is a mathematical problem based around chess. But a polybius square fits better with the the clue. $\endgroup$
    – rhavelka
    May 19, 2021 at 14:46
  • $\begingroup$ Can we get a hint? I've been coming back to this puzzle for the last month trying to figure something out or see if there is some insight that someone else has. $\endgroup$
    – rhavelka
    Jun 4, 2021 at 18:14

1 Answer 1


Okay.... I googled "A game that doesn't exist" and wound up with "Polybius (square)" which also came up in the commentary below. Hadn't heard of that before.
A game that has existed for over 1500 years" presumably refers to Chess. I thought that might be the 'key' for a simple version of the square or an 8x8 square but it didn't work, nor did other keys like "Polybius", so I abandoned this effort for some time.
Coming back to this puzzle, I did some research on Polybius squares and discovered...

There is something called a 'hybrid polybius playfair cipher'. I don't understand it completely but something that caught my eye was that the resulting encoding is a string of numbers of length N where N is approximately twice the length of the plain text.
EDIT: Like I said, I am not very knowledgeable about this cipher stuff. I think the BASIC Polybius cipher ALSO maps to a string of numbers of length N where N is twice the length of the plain text, so that is what I ended up using. I just had to look at the hybrid one before I realized what the basic one was doing.

You see where I am going with this. The answer is Xxxxxxxxx, 9 digits, and there are 18 marked destination squares on the board. So, we need to map each destination square to a number, and then decrypt it using the above algorithm.

An obvious way to map each destination to a number is by mapping the minimum # of hops the knight must travel to reach the square.
I came up with this table:
1 I
3 II
1 IV
3 V
3 VI
1 IX
5 X
4 XI
3 XV

This gives us encrypted text of "13 11 33 44 15 42 24 33 22" which I plugged into a basic Polybius decoder.
Again, using 'CHESS' as the key didn't produce a valid result. But then I tried no key (plain alphabet A-Z without J) and got the result:

Which seems like a suitable answer for a knight's journey! Nice puzzle!


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