This post by HTLit points to a very interesting and helpful article by Michael Mateas. Isn't it fantastic how we find things?
Recent interest around Eastgate in the role of agency in narrative immersion has led me to a fascinating essay by Michael Mateas, co-author of Façade. Using Aristotle’s theory of drama as a starting point, Mateas diagrams the role of agency in interactive drama, adding an additional model of choice and causation atop Aristotle’s diagram of narrative causation. This addition results in the proposition that “a player will experience agency when there is a balance between material and formal constraints.”Leaning heavily on previous work by Murray and others, the essay provides and interesting perspective for anyone interested in agency and its relation to interactive narrative."