Games offer unique possibilities for learning, and text-based interactive fiction ("IF") in particular lends itself as a low barrier to entry for instructors and students wishing to build interactive narrative games. Understanding by Design provides a framework by which to determine the best possible places for instructor- and learner-built IF in any given course, whether face-to-face or online. A thick description of how an instructor conceived and developed two IF games follows, explicitly tied to course-design considerations like learning goals and assessment performances. The value of IF as a student project is explored, and finally an appendix provides resources for instructors and students to begin building their own interactive fiction.