Go

There is a game, Go, which is an abstract strategy board game for two players, in which the aim is to surround more territory than the opponent. Read about it, it’s interesting. It is played for hours and days, and its difficulty is in its simplicity. You only have stones, white or black, and you just need to arrange them to cover more territory. This apparent simplicity gives incredible complexity, because there are no winning strategies. Every new move can change the balance so that you end up with nothing. You may be greedy, trying to grab more territory or not keeping an eye on it — and here your opponent puts his stones some way, and there your territory is no longer yours.