Way back in 2000, two researchers, Will Glaser and Tim Westergren, began what was then called The Music Genome Project. It was designed to categorize music by more than 400 different "genes" or characteristics of the music. The goal was to build a better music recommendation engine.
Today, this project is better known as Pandora.
Glaser and Westergren's fundamental insight was that breaking music down into broad general categories such as Rock or Pop or Country wasn't very useful when it came to making recommendations. Some people liked music with male vocalists or heavy beats or a fast tempo and no one liked all of country music or everything produced that was labelled "rock".
In fact most people liked a little bit of everything. Sure, they had genre preferences, but that didn't keep the Jethro Tull fanatic from liking (and buying) the occasional Mike Oldfield album (ahem...not that I know anyone who would do such a thing...).
Thus the Music Genome Project was born. By analyzing the genetic makeup of each song, the Project wasn't just able to better dissect individual pieces of music. It was actually able to make reliable cross genre recommendations. Oh, you like this driving, 120 beats per minute, sung by a female vocalist with lots of guitar distortion rock anthem? Then you might also like this hip-hop track with many of the same musical genes!
What Does This Have To Do With Game-based Learning?
This isn't going to sound that earthshaking but it was to me the first time I realized it: All games teach. You can design a game that will explicitly (or implicitly) teach something like math or grammar but you don't have to. With all of the good games, both video and tabletop, that are out there, it is not difficult to find a game that can be used to teach almost any K-12 and many university level subjects.
How many classrooms routinely use Monopoly, for example, to help teach basic addition and subtraction or units of currency? Monopoly certainly wasn't designed with this purpose in mind but it serves that purpose nonetheless.
While I might be bold in my assertion that every subject is covered, I would argue that, if I am wrong, I am not wrong by much. This is the golden age of gaming. There are more games being produced (and more good games) than at any other time in human history. The selection is already immense and growing. In fact, it might be more accurate for me to say that, while I might be wrong, I won't be for much longer.
Given the prevalence of formal standards in modern education, however, it is pretty easy to imagine (though infinitely less easy to actually do...) professional educators and gamers sitting down together and dissecting every game for the learning objectives that each game addresses (i.e. the things each game teaches).
Eventually - and, of course, you would start with the most popular games and the most important learning objectives - you would have a database that could answer the question, "What game teaches this?" Almost certainly, multiple games will cover the same learning objectives and some games will cover more relevant learning objectives than others. It is conceivable that a teacher would be able to query this database and find a single game (See image below) that adequately addressed all of the learning objectives for a particular block of instruction.