“Update on the recent sighting of the asteroid approaching Earth: Unfortunately… we’ve done the math, and this asteroid is too deadly for anyone to survive. The impact and the radiation will kill us all. Earth will die. Completely.”
“How much longer do we have left?” the news reporter asked the NASA agent.
“...About 100 days. Humanity has 100 days left.”

Riots ignited. Crime rates skyrocketed. Fathers and mothers left their families. Food, hoarded; famine, born.
Rumors spread on how to survive. Some organizations claimed to be setting up rockets in remote areas of the world so they could get to space before Judgement Day. Some said their bunkers underground would provide enough protection.
People ran rampant, doing anything to get to where they thought they could survive. They stole supplies, killed people for more supplies, kicked families out of houses and used them as their own bunker. 
Everyone asked themselves, “How do I save myself?”
By day 30, thousands had already passed away. By suicide, murder, a pandemic. All tensions between the corrupt fiends we call world leaders ceased. Most fled, hiding from the public eye; the few left tried to unite humanity but failed. There was no point. Everyone was going to die.
Day 60: millions gone. Forests around the world caught fire and burned. Pollution clouded the now-red sky. The survivors were those unfortunate enough to be immune to the pandemic. 60 days.
10 days left. The few thousand remaining humans had 10 days left. There was no hope. Depression ran rampant. What is there to live for? Humanity had 100 days left to celebrate, spread love, feel life, but they wasted it. They wasted it on something inevitable.
The 100th day, at 8:15 AM, the asteroid hit. The whole earth shook violently. If the shakes didn’t kill you, the radiation, taking mere hours to cover all of earth, did.
Every human, animal, tree, flower, ounce of life died that day, and then our story was no more.