I'm going to play the Devil's Advocate here...
IF he can show that the manufacturer of the game INTENTIONALLY engineered the game with the purpose of creating an addiction (as defined and diagnosed by a professional, such as in the DSM IV and by a psychologist or psychiatrist) that proved harmful to the individual using it, then why would he not be able to bring suit against the manufacturer of said product? I believe this precedent has been set when the tobacco companies were sued. I also feel that this is a more apt analogy than one might suspect since video-games are often seen by the majority of society as non-beneficial and even harmful, the same as tobacco. (Of course, he'll need a good body of scientific evidence showing the harm that games can do, much like was needed before society finally turned the legal channels against the tobacco industry.)
Of course, the trick here is to show that the product is truly addictive. This was something not shown in the cases against the fast food industry, and thus their suits were dismissed. (Just because evolution makes us crave fat and sugar - and the fast food industry makes foods with these that we buy - does not mean the fast food industry engineered the product to be addictive.)