Broadly, styles of play with an emphasis on challenge and/or competition. Coined in May 1997 on rgfa by Jim Henley. Within the Threefold Model, it is defined as the style which values setting up a fair challenge for the players (as opposed to the P Cs) -- which may be tactical combat, murder mysteries, politics, or any other test of player skill. In later versions of Ron Edwards' GNS model, it is characterized by the phrase Step On Up. It involves performance with risk, conducted and perceived by the people at the table. The social, real-world risk is usually a minor amount of recognition or esteem.

References:

• "Re: Definition of Simulation"(approve sites)
• The Threefold Model
• GNS and Other Matters of Role-playing Theory
• Gamism: Step On Up