I REMEMBER THIS!
I don't know if you've ever had the experience of picking up a book or a toy, maybe at a garage sale, that you played with as a child but had completely forgotten about and getting this electric sensation of recognition in a rush of memory. Sometimes I even get whiffs of scent. When I saw his images from the bottom of that article, I could smell the poor acidic pages, feel the gritty-soft paper between my fingertips.
Back to my epiphany. The sick puppies who wrote one particular CYOA included an easter egg. There was an ending that did NOT link to any story stem. Obsessive, notebook-toting child that I was, this so riled and confused me I took it downstairs to rant at my mother. "They forgot to put in a story!" I can remember shouting, "They have an ending with no match!" I completely missed the metaphorical point that mystery engineer man makes, that to find the planet you had to go outside all parameters, even those of the book. Freaking brilliant.
In a hyperlinked story, there's no such browsing, no such flipping, and of course, no shinyhappy planet leaping out at you. But. What if I did include an illustration? And what if it was the start of a new hidden story? Like a minor character's little mini-adventure? And this story would not be indexed. Just stuck in the middle for a reader to find at random. Too far outside the parameters of an ebook readers are unlikely to scroll through?