From IFWiki

For the IntroComp 2003 game by Ricardo Signes, see Agency (game).

Agency is the name of the active power that interactive fiction players enjoy when they direct the game in the manner of their choosing. It is agency that makes the players participants in the story, rather than just observers. It is also agency that makes the players responsible for their actions and for whatever consequences that follow.

A game that offers the players a high level of agency is one with lots of choices at every turn and many ways to change the status of its game world. By contrast, most CYOA games—which typically offer very few options at any turn, and where choices often have totally unpredictable consequences—are games where the player has low agency. Readers of a paperback novel and viewers of a movie have no agency; they are only witnesses and not active participants able to change the story.