Remember, if You Panic, You're Only Helpling The Zombies

Check out this Java zombie simulator. It provides a nice aerial view of a city under a zombie attack. Given that there's no plucky band of heroes - or even just Ash - to stop 'em, they'll take over the entire place as you watch, unless the city draws a populated box with no way in or out, like it sometimes does.

And apparently, when zombies have no-one to infect, they just tend to stand around in groups. Typical.