Hex is a board game played on a hexagonal grid (see board below).
Each player chooses a color.
Players take turns placing a stone of their color on a single cell.
The goal is to form a connected path of your stones linking the opposing sides of the board marked by your colors, before your opponent connects his sides in a similar fashion.
The first player to complete his connection wins the game.
The four corner hexagons each belong to two sides.
John Nash noted that the game cannot end in a tie.