This is the original plot developed by Brad King. It may have changed slightly since this was written but generaly this is accurate.

Storm Patterson stood at the crest of a hill overlooking the Greater Los Angeles Sprawl. The sun was just rising now, setting the dust-choked skies aflame with color. It was I+3, Three days after Impact. Three days after the end of the world. To those who saw the comet's impact, it was a blue-white bolt from the heavens. And Hell came in its wake in the form of a mutanagenic virid they were calling Hellspawn. The impact had scattered the virid into the upper atmosphere where it floated invisibly down to wreak havoc on those who had survived. The virid twisted its victim's bodies and minds and forged them into homicidal killing machines who knew no fear, only the desire to kill. Storm had already killed a dozen of the brutes, but his luck was running out. He too had contracted the virid. His only hope lie in the wasted city before him. A group of doctors and scientists calling themselves Aftershock were holed up in a fortified hospital, fighting away hordes of Hellspawn mutants. Storm had received a radio transmission promising a cure, if only he could make it there in time. It would not be easy. Even before Impact Day the city had been a dangerous place, home to vicious corporate soldiers, called Clans. Storm himself had been a Clansman once, but had escaped to the vast uninhabited robot farms that made up the countries heartland. He had grown tired of the killing, now it looked like he would have to take up the gun once again. He had no alternative's left. Aftershock is to be a first-person adventure set in the year 2139 in a world already torn apart by economic and social strife. Warfare in the heartlands of every major continent has forced the worlds population into vast cities called Sprawls. The heart land's themselves are vast robot farmed plots needed to feed the worlds booming population. In the Sprawls, power belongs to the Clansmen. Corporate soldiers whose loyalty lies with generations old ties to their Corporation. The Corps struggle for control over one another, turning to their soldiers when economic means won't suffice. The Sprawls are vast fortified cities where violence is part of daily life. Three days ago a comet hurtled from the sky, its fragmented head striking Earth in hundreds of locations. Earthquakes and tidal waves have laid waste to part of the cities. The head of the Comet also carried the deadly Hellspawn virid. A virid that alters the genetics of living beings and turns them into mindless homicidal beats. It is into this nightmare the player is thrust. You must make your way through the ruined city to the hospital at its heart in order to find a cure. Only then do you stumble across the threads of a much larger mystery. . . The goal of the Aftershock team is to create a world much more alive than Quake or Doom. We want the player immersed in the 3-D environment and drawn into the adventure. Much of our efforts will be going toward pulling the most out of the Quake engine to advance the immerse experience. We want to involve the player's emotions as well as satisfy our desire to blow things up. We want you to experience the End of Civilization. And perhaps, its new beginning.