Go is perhaps the best known of all Asian games. It is also known as igo (and although some masters are known to have quite big ones, ego is not a prerequisite to being a good player). It has been said — and rightly so — that go takes only a few minutes to learn but a lifetime to master. The number of possible plays has been calculated to be 10750.
It likely arrived in Japan from India via China around AD 400, perhaps as late as 700. It was very popular in the court during the Heian Period, but seems to have been claimed at some point by the warriors who considered it the strategy game of all time.
During the Tokugawa shogunate, it was organized into a rigid rating system and ranks were earned. It is now a professional game, and like chess and shōgi, there are those who actually make their living playing the game.
The go board has a grid with 19 lines by 19. Unlike shōgi, chess, or checkers, here it is the intersections that matter (all 361 of them), rather than the open squares. Black has 181 stones, white has 180. The best stones are made of slate and shell, although today even glass stones can be found, and common folk like students and amateur players use plastic.
There are only three rules in the game: two players, black and white, alternate in placing a single “stone” on any intersecting point of their choice (black moving first); if a stone is completely surrounded by enemy stones and there is no open area in the enclosure, the surrounded stone(s) is/are taken from the board and retained by the captor; and no move that would cause the reversal of the previous move may be permitted.
Captured stones count as one point each.
The game ends when all the stones have been placed or there is no longer any potential for capturing the opponent's stones or gaining territory. Then, all the captured stones are placed in the opponent’s vacant spots. The player with the most vacant area under his control wins.
That’s all you need to play. Go to town. No pun intended.
There is an interesting pastime called gomoku narabe (“five-eye line-up”) which was played in Period on a go board. (Nowadays it is played on a smaller grid of 15 by 15 to keep people sane.) It arrived in Japan from Korea around the eighth century. In play, it is similar to tic-tac-toe. The goal is to be the first player to get five of your stones lined up horizontally, diagonally, or vertically. Players alternate, with black placing the first stone. The entire board is open for placement.
It is a very simple diversion, but dangerously addictive. Be careful. You have been warned.
American Go Association, with news, resources for tournaments, as well as links to tutorials and online games.
Go Game Guru, with news, online resources, and store.
Igowin, a freeware 9x9 board. Good for learning the basics.