The L Game

A very simple game that is not that simple to complete.

The simply called "L Game", is in fact a game called "The Knight's tour" that represents a sequence of moves that a knight can perform on a chessboard such that the knight visits every square only once.

This game has spawned a mathematical problem, "The knight's tour problem", which was firstly investigated by Leonhard Euler in 1759, and the solved by H.C. Warnsdorff in 1823.

The earliest surviving knight’s tour is attributed to al-Adli ar-Rumi who lived in Baghdad in 840 AD and is known to have written a book on an early form of chess played in the Middle East.

On an 8 × 8 board, there are exactly 26,534,728,821,064 directed closed tours. The number of undirected closed tours is half this number, since every tour can be traced in reverse. There are 9,862 undirected closed tours on a 6 × 6 board.