I say video game, you say videogame
But I did just discover the Videogame Style Guide put together by David Thomas, Kyle Orland and Scott Steinberg. (Note the one-word approach.)
Cool -- coming as I do from the philosophy that says you can never have enough style guides, since language these days is more about triangulating spelling, style and meaning, rather than having it cast in stone.
You can buy a copy for $14.95 ($24.95 if you want the hardcover), or they have a free downloadable e-book at http://gamestyleguide.com/VideoGameStyleGuideeBook.pdf (we're all about free here at the CSJ Spin Dry and Bocci Center).
The work is based on the International Game Journalists Association (Lyndsey M. are you a member?) and Games Press. Yes, it differs with what little guidance AP offers (start with video game vs. videogame). But I also like the authors' orientation and acknowledgment that while style can never be written in stone (and especially in technology, right?), a consistent style goes a long way toward showing the maturity of the journalism involved. Orland's introduction, "A Question of Style," even though it is cast as a plea for game journalists to get their collective act together, is worth reading in every editing class to help the understanding of what style is and is not.
And as Dan Hsu, editor-in-chief of EGM:Electronic Gaming Monthly (you'll find some of the magazine's content at Hsu's 1UP.com), puts it in the foreword, we're not talking kid stuff. The average age of the readers of his magazine is over 21, and the average age of gamers is over 29.
So while you might not immediately convert to "videogame," do resist the tendency in some quarters to dismiss such things as just tools of the corporate world trying to foist various idiosyncrasies on us. The guide seems to be an honest, well-thought-out effort. Download (or buy) and scroll or thumb through it. You'll be better informed as a result.
(As the authors note, all such guides are a work in progress. My only wish is that they would somehow implement an e-mail update to notify if they change or add anything. They do have a Wiki that includes an online version of the guide, but no RSS or other feed that I can see.)
(For an interesting and somewhat dissenting post, see Language is the People's.)