Creativity Inc by Ed Catmull
Insightful and thought provoking book on what it takes to foster true creative genius in a company, in this case Pixar. Everyone who seeks to work on large scale collaborative projects should read this book.
Thinking Fast and Slow by Daniel Kahneman
How does our brain actually work, and what can studying it teach us about how we interact with others? A wonderfully written exploration of all the biases you don't even know you have. A vital text for better understanding how we communicate with each other.
The Hero with a Thousand Faces by Joesph Campbell
You've almost certainly heard of the Heroes Journey, but have you read the original source? Every game designer should read this text. While parts of it haven't aged as well as others, it's still great to dive into the source material.
Picture This by Molly Bang
Brilliantly minimalist, this short and succinct book uses geometric shapes to explore the power of shape and composition in visual imagery. Games are after all, a visual medium.
Drive by Daniel Pink
What motivates us and why? This book explores those questions and challenges some of the old industrial age assumptions about motivation at work. A great read for those who have to manage any creative process.
The Design of Everyday Things by Don Norman
If you don't know what affordances are, you will after reading this seminal design book. On the surface this may all seem to relate to more traditional design disciplines, but the underlying philosophies about how to approach any form of design are every bit as important for game designers.
The Visual Story by Bruce Block
A wonderful exploration into the core tenants of visual design in film and digital media. It's a masterful deconstruction of how, and why, visual storytelling works.
Your Brain at Work by David Rock
Another look at motivation, inspiration, and how we handle conflict and fear. Aimed at general communication in a professional environment, this book has many helpful insights into how our actions influence others. Another important skill for creative collaboration
On Writing by Stephen King
It is always interesting to hear the thoughts of a master at their craft, and this book on writing by the master of horror himself is one of the best ever written in my humble opinion. Great material for any creative sort to absorb.
In the Blink of an Eye by Walter Murch
Possibly the most obtuse one on this list, at least in terms of what it might teach a prospective game designer. However I like this one because it is a brilliantly written book on how to approach a technical and creative craft. It is not a technical manual of any kind, and instead focuses on the mindset required to work as a film editor.
So that's my list, consider it a starting point. There are many other wonderful books that focus on other creative mediums that we, as game designers, can learn from if we just start to look in the right places!