Within the Big Model, the "aesthetic priorities and any matters of imaginative interest regarding role-playing", or more generally, what a given player strives for and feels satisfied by over the course of a given game's reward cycle. Sometimes abbreviated as "CA."

Three major categories of CA have been identified (in what is sometimes called the GNS Model) as being the most likely to conflict with one another at the gaming table. They are known as Gamism (often characterized with the phrase Step on Up), Simulationism (characterized by the phrase The Right to Dream?), and Narrativism (characterized by the phrase Story Now). It's important to remember that these are categories, not a closed set of essential desires into which everyone fits exactly; and that these categories were derived solely from asking what causes conflict at the gaming table, whereas other questions might lead to other CA groupings (or no particular groupings at all).

This concept was referred to as "Premise" in Ron Edwards' second GNS essay -- but in the current incarnation "Premise" is specific to Narrativism.

References:

• GNS and Other Matters of Role-playing Theory
• GNS will fade into the background of RPG Theory
• GNS: What is it?
• Gamism: Step On Up
• The whole model - this is it