Any person who plays video games for a hobby. You have your recreational gamer who plays games only once or twice a week. You have your typical gamer who plays games once every day or every other day for a couple hours. Then you have the uber-gamers who dedicate their life to playing video games, either because of an unhealthy addiction or something job related.
Bill is pretty good at that game, no wonder he thinks he's such a great gamer.