I've also voted [1] - I myself picked up English and Japanese mostly by means of fun - video games, anime, movies... you name it. Many English-translated playstation and computer games, such as Final Fantasy series, helped me learn (about?) English. The only thing I've wished those games had was the English voice that you can turn on or off by choice. (Many of today's games seem to have implemented such measure)
I've read your plans and concepts for your educational game, and they sound pretty good although I wouldn't know for sure before I actually see the game.
I'd like to put some opinions on it.
I don't know how my attachment will show in this post but take a look at it. If you have to download it to see it, you may want to do so.
This is a screenshot of a Japanese
Ero-geh, or 'love affair simulation game for adults'. Some of you might be laughing by now, and yes, it is despised by many sane people, but has its niche in Japan. (and exclusive in Japan!)
The game comes with full voice for almost every dialog, and one very neat thing about the game is that it comes with this 'history' feature, where you can browse through previous dialogs and when clicked on the small voice icon you can listen to it as many times as you need. I'm guessing the same thing could be applied to the video games meant to teach English.
By repeatedly listening to parts of dialogs on which learners want to focus they can not only improve their listening comprehension but their overall pronounciation also. I got little carried away and went sort of off-topic but I thought I'd give my two cents on this as an
ESL student.