Hi guys, I enjoyed your game - well done. I agree with Astrid that it is an innovative take on the theme. Dyslexia is a subject I know little about, so I felt this was also nicely educating in how a child might perceive it.
Nathan's voice is strong, and the music added to the melancholy. I liked the gradual revealing of back story, hinting at his mother's absence. I enjoyed the concept of friendly characters speaking through the rabbit - the 'Literate' world definitely came across as a place of solace, and the loss of this world makes for a bittersweet ending.
If you've not tried this editing technique already, I'd definitely recommend leaving the text to settle in its final stages, then returning with unfamiliar eyes to print it out and read it aloud. I've found this works well for refining character voices and honing style. It may help refine areas such as the adult voices, so they are as befitting as Nathan's.