It’s just an idea, but it’s doable: a book application which has parallel narration paths and narration styles. When you open it, you select your mood and what follows is a plot path which best fits into how you feel (and what you expect from a book).
So if you want to calm down, you have the same story delivered in a much more descriptive way. If you want more action, you get a thicker plot.
When reading e-books, you have them all on one device. You read several books at the same time. You pick up the right one to answer your current emotional need (match your mood).
Why choose from many books if your need can be answered by a single one?
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