As an integration specialist I don't often get to teach kids. When I do it is usually a webmaker or digital citizenship activity.
Jokaydia (firstname.lastname@example.org) uses minecraft and Second Life to teach digital citizenship skills, but again not a classroom situation.
You might want to check out the World Peace Game https://novoed.com/education/blog_posts/23621?data_type=report
Games are a great way to teach, but I would suspect they are being forced into a niche/disruptor role because it is too difficult to "cover" the right material thus not acceptable in the regular classroom