A) A person
attempts to win by all means at tabletop role-playing games.
B) A person
who seeks to accomplish everything possible within a videogame - meet all secret goals, get every item, unlock every secret, etc.
A) "Last I heard, he had given himself a man-sized sword. What a powergamer."
B) "You bought
and upgraded every 200 cars in that game? Man, you're a powergamer."