Tourneyfags are people who make up (often on the spot) and play by non-official rules for video games. These rules are crated as to best suit their play style and/or play ability at any given time.
A tourneyfag of a profound competitive nature is a person who feels that "fun" ruins any aspect of competition from a given video game, and thus any articles that may provide a random occurrence or event within a video game must be removed (or disregarded where appropriate).
Tourneyfags in every sense of the term are complete opposite of generally accepted and widely regarded "tournament players" of any given sport or event who, play by a predetermined, entirely approved set of rules, which are official, and govern each player competing. Within these rules they do not allow for self governing, a referee and/or judge takes upon that responsibility.
Brian wanted to play a competitive game of super smash brothers, but david the tourneyfag would only agree if the rules he made up on the spot were the ones that would dictate their gameplay. No items, fox only, final destination.