Just for fun, let's do this over again.
No game will ever be able to teach you enough Japanese to play games. There just isn't any way that's gonna happen. The casual crowd just isn't interested in learning the 2000+ characters it takes to read proper Japanese.
If you do, however, wish to learn Japanese, and classes are not an option, you should get the Genki textbooks. I used them in my classes, and after having been forced to use other lesser works as well, I can truly say that Genki is the best option. It's great for self-study. Then when you get the books, head on over to
http://renshuu.org/, which will drill you in the vocab and characters you learn. 5 years down the road, you may be able to start and dabble in the type of games you are likely to be interested in. Just to make it clear, even the advanced classes in the undergraduate level will not leave even near being able to play something as dense as say, a Japanese RPG.
Good luck