Your name is Steve Protagonist. You are a cop. And this morning you're in a bad mood because you just found that your coffeemaker is not working.
Also, billions of hungry zombies have taken over the world.
You have only one hope for survival, and that is to make it to the nearby military base. It wouldn't be much of a problem if not for the legions of brain-hungry zombies in your way.
So you'll just have to make a run for it. Zombies aren't particularly smart, and there are weapons scattered about, so there's a little hope for you. Also you might be able to rescue some friends along the way who can help you out.
Oh, and you have to do all of this with only one tap. Good luck!