Halo series. Standalone novels

Before the Human-Covenant War engulfed Halo, the planet-colony Reach came under attack by the Covenant, and Earth's specially trained and augmented warriors, code-named SPARTANs, stood alone to fight for humanity's survival.

"When the Helljumpers respond to an SOS call from the remote science colony Ariel, they stumble upon something that catches them off guard: the colony is deserted, seemingly abandoned by every man, woman and child who ever lived there. The lone corpse on the planet's surface, a communications officer, appears to have died of fright. The discovery of a large Covenant military presence raises more questions than it answers. And when two Helljumpers...

"An original full-length novel set in the Halo universe and based on the New York Times bestselling video game series! Just hours following their climactic battle on the Forerunner planet Genesis, the Spartans of Blue Team and Fireteam Osiris find themselves running for their lives from the malevolent machinations of the now-renegade artificial intelligence Cortana. But even as they attempt to stay one step ahead, trouble seems to find Spartan Edward...