In 2010 Chang Hsu, owner of four of the top seven go titles in Japan (where he is known as Cho U), began teaching his four-year-old daughter to play–on a four-by-four board. To make the game interesting, instead of black and white stones he used red and green discs resembling apples, with a board designed to look like an apple tree. His daughter was quite pleased.
In January 2012 the results of his experience with his daughter appeared in the form of a book entitled Yonro no Go no Hon (Four-Line Go Book). The book takes the reader through the basic rules, techniques for capturing stones, territory, double life, and ko, and has a final challenge section. Mainly it is a collection of 100 puzzle-like problems, red to play and win, each with the answer shown in diagrams on the next page. The text is in Japanese, but the diagrams are self-explanatory.
As the author says, the problems are not particularly hard, but they are not trivial either. They take you through snapbacks and eyes and then into ko timing and under-the-stones tricks. You soon realize that they come from a clever and creative mind. In one problem, for example, red wins by sacrificing seven stones–on a four-by-four board (see image at the bottom)! The problems do not teach much about standard life and death shapes or tesuji–the board is too small for that–but they are an excellent way to practise reading a situation out, move by move, until you see it completely and arrive at a definite conclusion. For learning that all-important skill, the four-by-four board may be just the right place to start.
The publisher (Gentosha) also sells a boxed set including the board, the apples, and a booklet with an earlier set of elementary problems. For those interested in go visibility, this is an excellent tool. The board does not take up much space at a cafe or bar, a game does not take more than a few minutes to finish, and the apple tree is a good eye-catcher. It will not be hard to get someone interested, and then you can use the puzzle problems, or you can just play a few games (the interesting challenge is to make sure your novice opponent wins most of them).
Better yet, there are now i-phone/i-pad app versions available in three languages, with the apples replaced by animal characters in a story mode and by normal black and white stones in a serious mode. Easier to obtain than the book or boxed set, these apps are a bargain for players at all levels, including dan levels. Highly recommended.