Hex is a game for 2 players.
Rules: connect your sides with your stones to win. That's it!
Good players also use the swap rule: after the very first move, the second player can decide to swap the colors: he then keeps the stone that was played, and it is again the turn of the other player (but with the color now changed).
Wikipedia page for Hex
This game is easy, quick and fun to play.
It's appealing to beginners, yet remains very interesting for expert players.
Print your own Hex board! Here are links to print Hex boards suitable for standard Go stones: