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Where do zombie hordes stop, and do they keep moving?
Zombies always stop in front of the first hole in the fence line on their path, whether or not you built a barricade there; they do not skip a hole you barricaded. They resume from the arrow tip when the next Zombie card is revealed, and once all three Zombie cards are out they stop moving. The "empty space in the barricade" means a hole in the fence line itself, not a missing house, so a numbered house in front of an unbarricaded hole is still at their mercy.