Ahhh well there are games that have basic Japanese grammar are the “Boku no Natsuyasumi” series. Sorry if I seem to be pushing but these are fairly relaxed Japanese vacation exploration games where you roam the Japanese countryside. What I mean by the grammar too is they follow Japanese conventions, nothing radical.
As a general rule of thumb though I strongly suggest getting a Nintendo DS to get “Kanji Sonomama” which is a Kanji dictionary. It has a library of many Japanese dictionaries in it and you obviously write the Kanji with a stylus.