Codename: Outbreak PC Game

During the routine observation of nocturnal sky astronomers have registered a new object in the Ursa Major constellation zone. It was indexed as JK4538-XK. According to observation data, the object was of midsize comet class. The subsequent computations confirmed that the comet was inbound from another galaxy. Such a rare event became a worldwide sensation in the wink of an aye. Moving at a tremendous speed the guest from another galaxy could soon be seen with a naked eye in the sky at night. However, the exultation vanished into thin air as soon as the scientists reported about probabilistic trajectory of the comet: it could collide with the Earth. After verifying the calculations, state authorities began preparing for the possible catastrophe and evacuating the cities. Humans got ready for the worst.

Passing in dangerous proximity to the Earth, the comet scorched the atmosphere and hundreds of meteorites poured their fiery rain down causing death and destruction, evoking tsunamis, hurricanes and earthquakes. When ash and smoke cleared away, the survivors could see the cities lying in ruins and the meteorite-pitted lands. A sluggish reconstruction after the devastation was begun.
Though meteorites lying deep in craters were not exactly dead stones - they gave birth to new life around them. The recently frequent cases of people disappearing served the first foreboding. Some time later the communication with one of the military laboratories researching meteorite samples was lost. The rescue party sent to the lab faced vigorous opposition trying to get inside. The guard killed in the skirmish was partially absorbed by an alien organism, confirming the worst apprehensions of biological contamination.