Rogue Trooper: The Future of War by Gerry Finley-Day
The war between the Norts and the Southers chemically poisoned the entire atmosphere of Nu-Earth - so the Southers created the Genetic Infantrymen: blue-skinned soldiers who could breathe the toxic air, equipped with bio-chips to record their personalities in their final moments, for eventual re-corporation. But a Souther traitor sold the G.I.s out, and all but one were slaughtered. Now he stalks Nu-Earth on a mission of revenge, aided by his dead friends, now living in his gun, helmet and backpack. He is the last G.I. - the Rogue Trooper!