From the campaign:
The world has reached the first great apocalypse, You're either a brain munching zombie, an interstellar alien, or one of the few keeping them at bay... for now. Collect and trade matching cards to complete your mission for either an alien invasion, wide spread infection, or be humanity's last hope, and cure them all. But every card you draw has a negative and positive value. Will you inadvertently let the enemy win by passing the wrong card. Deception is just as important as luck.