A common term with various meanings, though most are similar. (1) General term for players who seek to make their P Cs as powerful as possible, often trying to find ways to manipulate or overcome the GM interference. (2) One of the four types in the Blacow Player Types which was adopted by Robin Laws for his seven player types. (3) Within Ron Edwards' GNS theory, "a potentially dysfunctional technique of Hard Core Gamist play, characterized by maximizing character impact on the game-world or player impact on the dialogue of play by whatever means available."

References:

• The Munchkin's Guide to Power Gaming(approve sites)
• Robin's Laws of Good Gamemastering(approve sites)
• Player Types (from Glen Blacow and Robin D. Laws)
• Gamism: Step On Up