Clark Aldrich once said that about educational games that:
    "Game elements are the spoonful of sugar that helps the medicine go down." (“Learning by Doing”, p. 85)

This is the attitude that learning is boring, and that we need to add the game elements to an educational game in order to make it bearable. I fundamentally disagree with this approach to educational game design. One of the central themes of Raph Koster's A Theory of Fun for Game Design, is that fun comes from learning new skills. Games get boring once we master the skills needed to play them, and they get frustrating when we aren't able to gain enough competency. That's why it's important to make sure your games difficulty curve is optimized to constantly be just challenging enough.

It's also why I say:
    "Learning should come from the game elements themselves."

We want to avoid sugar and medicine. We want to create a tasty and healthy meal! Of course, that's easier said than done. The challenge when designing an educational game, is to figure out a way to turn the act of learning into a game mechanic, or at least make sure that in the process of learning the skills needed to play the game, they'll also pick up the knowledge or skills you're trying to teach. It's not enough to just tack on a multiple choice quiz about agribusiness to a balloon-popping game, or to ask flash-card style math questions that cause alien ships to explode. To get the full benefits of Game Based Learning, you need to test skills in a relevant way. Questions about agribusiness would naturally arise in a sim-agribusiness game, for instance. Of course, games can be relevant without being realistic. You could train up someone's algebra and trigonometry skills by making a game about firing projectiles at aliens using mathematical equations to describe the trajectory.

Today's example of a game that takes this approach is Light Bot. In light-Bot, Players use programming concepts to solve puzzles. Programming is the game element.
Light-Bot is a good pre-introduction to imperical programming, and it does of good job of teaching people how to use Functions, and it also demonstrates why Functions are useful. It doesn't use conditionals, control loops, variables, or parameters, but one could imagine an advanced version of the game that did. Light Bot is a successful casual game by Coolio-Niato, sponsored by Armor Games. It probably didn't set out to have much educational value. My guess is that the creator just realized that programming a robot would make a fun game, and learning some basic programming concepts was a side effect. Our challenge as educational game designers is to get the same outcome, but from the other side. You know what you want to teach, but how to you make that fun?

Play Light Bot