I personally feel a game is something we do that can take part in that can be mentally and physically stimilating. A game needs to have specific rules and an ultimate role.
Wolfgang Kramer of 'The Games Journal' talks in greater detail of what a game is and all of the components of a game.
I am not a massive fan of gaming. I used to enjoy playing pro evolution soccer but I do not have the time to play on games these days. Championship manager 97/98 is possibly the greatest game that has ever been made!