Thunder Gun

The Thundergun is a Wonder Weapon featured in Zombies. Thundergun is a large, cannon-shaped weapon that fires blasts of incredibly strong compressed air. It has no iron sights, meaning it must be fired from the hip. It is able to kill large numbers of zombies with a single shot, sending them flying backwards or up. Those who are not killed by the blast are thrown backwards and will remain on the ground for a few seconds before getting back up. The Thundergun holds two rounds in its magazine, and has twelve reserve rounds. The Thundergun can only be reloaded when all shots have been fired

Zeus Cannon
The Zeus Cannon is the Pack-a-Punched version of the Thundergun. It has four rounds per mag and has 24 backup shots.