I am not going to repeat the comments from the other reviews. However, I would like to add to those reviews...
I bought this game for myself and my 12-year-old son to use. I studied spoken Japanese 20 years ago and wanted to brush up my Japanese, learn the kana and some kanji and expand my vocabulary. I am now on lesson 29 and my son is a few lessons behind me, and I have to say that so far the game has proved excellent for both of us. I have now learned the Hiragana and I am working on the katakana - thank you previous reviewers for the warning about stroke order as I had not realised there was a problem.
Overall I am very pleased with this game, although I would have a couple of suggestions for the developers if they plan to bring out a revised edition: (i) an expansion of the hiragana and katakana exercises would be good so that you could, for example, go into a game to test only your hiragana; (ii) what has sometimes happened is that I have supposedly 'mastered' a set of words but I really only know the romanized versions and I need more practice on the kana characters (I am not on to kanji yet) and at this point the game takes me on to the next set of words before I feel ready. This could be overcome if the games did not start testing you on new words until you had gone through the lesson in which the new words are introduced; and (iii) it would be good if in Options you could click a button to make all words shown in kana rather than in romaji (and change the option back as needed) to help with learning the kana in some of the games.
Sorry if all that sounds complicated. They are actually only small criticisms of an otherwise EXCELLENT and FUN piece of educational software.