Expanded universe novels are a popular trend and have been for decades. Star Wars has a massive and rich one (if now controversially kinda not canon anymore) and Gears of War and Halo both have some great entries from some great authors that helped to flesh out the in between and motivations behind the events of our favorite franchises.
The novel will be titled XCOM: Resurrection and is penned by Greg Keyes and explores the rise of ADVENT cities following Earth’s surrender and follows Amar Tan, “a promising recruit in the barely-hanging-on guerrilla resistance network that still dares to combat ADVENT outside of Gulf City.”
XCOM: Resurrection will release on November 10, 2015.