The toroidal problem seems simpler because of its symmetry. Unlike on the classic board, all the diagonals are the same length, and every queen can attack the same number of spaces: 27.

The n-queens problem began as a much simpler puzzle, and was first posed in an 1848 issue of the German chess newspaper Schachzeitung by the chess composer Max Bezzel.

First, they needed to be tackling the right problem, since n-queens is easy and n-queens completion is hard. Second, it is not enough to solve instances on a standard 8-by-8 chessboard.