Hex

Hex is a two-player board game invented independently by two mathematicians, the Danish mathematician Piet Hein at the Niels Bohr Institute in 1942 and John Nash at Princeton University in 1947. It was called Polygon in Denmark and was also known as Nash or John, but was given the name Hex when it was offered as a commercial version by the game company Parker Brothers in 1952. John Nash proved that the game of Hex cannot end in a tie. The game was popularized when Martin Gardner wrote about it in The Scientific American Book of Mathematical Puzzles and Diversions in 1959.

Hex board
Figure 1: Hex board

Rules

Hex is played on a diamond shaped board made up of hexagonal cells shown in Figure 1. It is usually played on boards of 11 cells on the side for a total of 121 cells. One player has red pieces and the other player blue pieces. Opposite sides of the board are designated red and blue and the goal of the game is to complete a chain of pieces between a player’s two sides. The players take turns, placing one piece on one of the unoccupied cells of the board. Each player attempts to advance their own chain or block that of their opponent. The first player to connect both their sides wins the game. The four corner cells each belong to both sides. The center hex cell is the strongest starting position which gives the first player an advantage. The swapping rule allows the second player to choose whether to switch with the first player after the first player makes the first move.

The best offense in Hex is defense. Attempting to block your opponent will naturally lead to creating your own chain across the board.