Hex is a two-person board game where players try to connect opposite sides of a hexagonal grid. It was invented in 1942 by Danish mathematician Piet Hein, who wrote about it in the Danish newspaper Politiken. Hex is interesting because of it's incredible depth/complexity ratio: the rules are extremely simple, yet it has five billion times as many possible positions as chess (when played on an 11x11 board). This high depth means that the game remains difficult for computers to play.
Hex+ is an online client for playing Hex against both friends and strangers.
When it is your turn, click any empty cell to mark it with your color. Try to make a contiguous path from one side of the board to the other: top-to-bottom for red, left-to-right for blue.
There's only one other rule: because blue is at a disadvantage from moving second, on his first move he has the option of swapping colors with the other player. Swapping isn't mandatory, and can only happen once per game, on the first move.