I subscribe to the Angry Joe definition of a Gamer.

A gamer is a person who is passionate about what it is they do. A gamer is the one who is waiting in line release day. A gamer will argue and debate what games are good and what ones are not, and have many reasons as to why. A gamer is the type of person who enjoys the smell of a freshly opened game case.

I don't really get why someone who just plays games from time to time can be called a gamer. Would you call every person who goes to watch a movie a movie buff? Would you call someone who drinks every so often an alcoholic? Would you call a 30 year old man who punched out a 15 year old kid for being a dick an ass kicker?

No my friend, you would not.