Chess A Knight's Journey

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...