From Introduction:
GM's Toolbox: Scenario Points
As you may have discovered, creating an endgame or final Victory Condition when the overall impossible odds of a zombie outbreak are facing you is not an easy one. Perhaps a small victory is a precursor to an even larger victory that could be on the horizon, but more often than not, your players are forced to survive against very grim odds. As Chuck Palahniuk wrote, "On a long enough time line, the survival rate for everyone drops to zero." Given that ultimately, the entire point of this game is survival, how do you construct a scenario that is set up to fail by virtue of having an admittedly impossible goal?