My favorite standalone unicorn book is part of another series called Fairy Realm by Emily Rodda. That book is #6 in the series and is literally called The Unicorn. This is much more of a kid's book and is only a 6 hour audio book, but it is still one of my comfort books. 
I've recently been exposed to the Netflix show Unicorn Academy and love it. I was super excited to see the new summer special pop up. 
My best friend IRL is StormcloudPegasus, and we met each other while reading the Redwall series at our local library. We've been best friends ever since!
Enjoy your game, and never lose your magic!
*TheMidnightWalker*