Gassers — Tony Monchinski

The Earth isn't what it used to be. Years after the Shower--a devastating meteor strike that wiped out much of life--the planet is an inhospitable wasteland. Much of humankind has migrated to other solar systems in other galaxies. A troop of battle-hardened Intergalactic Marines under the command of Lieutenant Randall, and his right-hand man, Gunnery Sergeant Gaddie, must return to the devastated planet to save one of their own from the clutches of Kodjoe, a ruthless African warlord. The threats they face are numerous: a continent overrun by Creepers, arachnid-like beasts with a taste for human flesh; Gassers, virus-infected, mutated men and women who represent a new stage in evolution; and Kodjoe's own private army of blood-thirsty killers and cutthroats.  But Randall's Raiders are going back to Earth, back to Africa, and back into battle.Because they know one thing: you don't leave a warrior behind.And they'll raze a continent to rescue one of their own.