Splice

At the dawn of the 22nd century we had finally done it. Humanity had finally ended all genetic disease. No more birth defects. No more cancers. We were even on the brink of virtual immortality; an end to all non-violent death.
The treatments were miraculous - nothing short of medical science's greatest triumph. A combination of gene and virotherapy techniques were able to rewrite a patient's genetic code on the fly. It looked like we might be entering a new golden age.
Within two years, the majority of the planet's population had received at least one dose of "the treatment" as it was colloquially called. No major side-effects had been reported, most everyone tolerated the treatment well thanks to advanced screening techniques and compatibility quotients. A small portion of people were unable to take the treatment due to a high risk for complication, but this was under 0.001%.
Fortunately (or perhaps more accurately unfortunately) for you - that describes you. Unable to receive the treatment due to incompatibility, you were left behind in this new era. Most people reacted to you with pity. Some with disdain, as if you were blighted - or infectious. In the end, this is what saved you. Or cursed you to live in this nightmare.
In the 10th year after the discovery of the treatment, something went wrong. No one really knows what it was, but people started to... turn. Some people spontaneously combusted. Some people became flesh-eating monsters. Still others were compelled to gather together in crowds and explode, sending razer-sharp shards of bone in all directions. As quickly as we had ushered in the new world it dissolved into chaos.
They're out there. Stalking the night. You can hear them banging on the door to your shelter - an old bunker where the last remnants of humanity, in all its imperfection, survives. Your supplies are running low. It's either slowly starve to death down here, or brave the streets up there in search of supplies. Quick and Quiet. That's the plan. Now let's get to it.
Areas of Note: The Bunker, Downtown, The Bodega, Wes Paul's Meat Market, The Abandoned Theme Park, Boardwalk.
Goal: Brave the streets above and gather supplies - bring them back to the bunker and survive a bit longer.