Writing with apps in mind opens a whole world of cross-disciplinary opportunities. Collaboration with other creative genres has been difficult and limited simply by the nature of writing and reading. Graphic novels stand as the hallmark of co-op effort by allowing room for both the visual and written aspects to flourish. In most other cross-disciplinary efforts, writers tend to be on the sideline, cheering at someone else's game. It is hard to invert the process and make literary content the focal point of a collaborative effort. An app can center on literary content complemented by a selection hailing from other creative fields: musicians, game programmers, graphic designers, you name it.
We live in a remix culture; we love sampled music, fusion food, multimedia approaches. Apps give literary content a way to play in our remix culture as focus, not just a bonus.