Fantasy Zombie Apocalypse

The Kingdom of Larion was peaceful until an evil necromancer unleashed a zombie horde. Though the necromancer was slain by heroes, the zombies had already turned many peasants and overwhelmed the kingdom's armies. Now, the King hides in his palace, leaving survivors outside the castle walls to fend for themselves. Without their master, the zombies shamble aimlessly, attacking whatever they encounter. A master of necromancy could control the zombie horde but it would be a difficult task.