Halo: Ghosts of Onyx

Blurb

Halo: Ghosts of Onyx is a military science fiction novel by Eric Nylund, based on the Halo series of video games. The book was released in October 2006 and is the fourth Halo novel; Nylund's third contribution to the series. Onyx was also the first of three Halo novels to be published by Tor Books, rather than the previous publisher, Del Rey.
Ghosts of Onyx is a piece detailing the creation of a group of supersoldiers known as the SPARTAN-IIIs to defend humanity against the alien collective known as the Covenant. After the events of Halo 2, the SPARTAN's training world of Onyx is beset by robotic attackers. The SPARTANs and their trainers must fight the robots and the Covenant as they work to uncover the planet's secrets.
Upon release, Ghosts of Onyx garnered generally positive reviews. The novel debuted on The New York Times bestseller list and became an international bestseller.