I wrote a companion piece to the game:

"Personalized white paper about the implementation, customization and usage of features in Unreal Engine 4 during the development of virtualy reality game ShowdownVR. It presents a strong practical case of why open source game engines are the future."

Amazon: https://www.amazon.com/dp/B01M076VQN

Everyone who bought the game can get their hands on the book by browsing into game's directory and opening "Bonus content" folder, where you can find your copy of the book along with other things. Happy reading!