Nah, that's just a 'gamer'.Well 'gamey' would describe the feeling of a game (or else the taste of wild meat!), whereas 'gamist' to me describes a person.
Not knowing much about this GNS stuff (and not being interested in learning more about it), that's how I always understood 'gamist'.Gamist- a design element that breaks immersion by reminding the player they are playing a game.
In 4e entering combat often feels to me as if we switched to playing a completely different game. It's a tactical puzzle with elaborate rules embedded in a roleplaying scenario. Roleplaying is definitely taking the back-seat during combat. It's more important to play your character efficiently than to emphasize your personality traits, at least until the situation is somewhat under control.