A feeling that, as an academic, happens every once in a while when you are scouring the literature on your research topic, when you stumble upon that title that both excites you and makes your heart sink. The title that says “hi kelly, your thesis has already been written by somebody else, move along”. I think everyone that I know has had this feeling at least once. For me, it has happened a few times – video games and identity (to be fair) isn’t exactly the most unique research topic out there in terms of ‘key words’. Today, I found this book, due out in May. On the one hand, I am really excited to read it, on the other hand, I am scared that it will say everything I have been working on over the last few years, making my research a moot point. Mind you, I had a similar shiver when I saw I, Avatar (and a few other titles)
To be fair, I know that more than likely I am panicking for nothing. My work is about the process of identity construction in video games (generally speaking), not the psychological influence of avatars on “real -world players”, I am not using Gee’s work as a theoretical foundation, and other than the “recommendations of terminology for future identity researchers”, which could really be useful in the long run, I have different experiences, ground my work in a different literature and (more than likely – or … hopefully) have something different to say and/or contribute something different to the world.
kellyboudreauphd.ca 
Ahhh yes that feeling seems to be one of the potholes in the academic road. One such pothole derailed my own MA thesis journey the first time around, so yes I, too, know it.
As for your own pothole, I’d say you should skim the book to reassure yourself. Given that the author has a background that isn’t sociology or necessarily even social theory, there is a darned good chance the approach will be totally different. You yourself have noted that already.