Making a "Worthy" Game

Ok, so our students have been reviewing games in the Play to Learn section of the Globaloria program. Several of the games are about the type of game genru that can be created. Now the question is...What makes a GOOD Social Issue Game? Do some serious thinking about this and post a RICH blog about how you can create a fun game and still cover a Social Issue, STEM (Science, Technology, Engineering, Math) or Civic Issue.