After round 16 on Der Riese, Hellhounds spawn at the same time as the regular zombies, but also still get separate rounds where they appear alone. When the last Hellhound of the round is killed, it will drop a Max Ammo power-up. When a Hellhound round ends in Der Riese and Kino der Toten, "Beauty of Annihilation" is heard. The same goes for Pentagon Thief rounds in "Five" and Space Monkey rounds in Ascension. "Five" and Kino der Toten, both from Call of Duty: Black Ops, feature a new kind of zombie called Crawler Zombies. The Crawler Zombies is a zombie that crawls on all fours (hands and feet). It emits an "aura" of Nova Gas upon death, unless it is killed by a Ray Gun, Thundergun, explosives or melee weapons. Apparently, the Crawler Zombies were a failed experiment by Maxis, according to Richtofen.
Besides some great new weapons, a specialist Wonder Weapon called the Gauntlet of Siegfried and a new kind of zombie shield called the Guard of Fafnir were added, much to the delight of the community. Interestingly, Gorod Krovi is the final map of the Call of Duty zombies Aether storyline that is entirely original and does not recycle areas from past maps.
Nacht der Untoten (German: "Night of the Undead") is the first map of the Zombies Storyline. It is also the smallest and simplest, as there are only three rooms in this map. The Zombies in this map are less deadly than the ones in other maps, as they do not reach through windows and they're the least smart in terms of AI. The Zombies also look more human in this map and they just groan and moan. This was the only map to not include Perk-a-Colas until the September 27, 2011 update that provided every map with Mule Kick, however, this only applies to Call of Duty: Black Ops. Because it is a last minute developer addition, this map simply acts as an introduction to the Nazi Zombies Game Mode and does not advance the Zombie Story Arc; it's more along the lines of an isolated incident for four unnamed soldiers. It takes various design elements from a bunker in the multiplayer map Airfield, the bunker in the map therefore earning the name "Zombie House." However, it has nothing to do with that map story-wise. The version in Call of Duty: Black Ops features the original power-ups, including the Carpenter power-up (which is first introduced in Der Riese) including the power-up icons, instead of the text and the remaining time at the bottom. Cold War weapons are available in the Mystery Box, zombies can now reach through the windows to hit the players, and a new musical easter egg called "Undone" can be found.
Moon is the eleventh map in the Zombies game mode, included in the Rezurrection map pack. It starts off at Area 51, otherwise known as, No Man's Land, where for the second time, Hellhounds spawn with zombies after a certain amount of time. Teleporters return, and the main area takes place on a base on the moon. The four original characters return as playable characters. It features new Wonder Weapons, one of which is called the Wave Gun, which has a dual-wieldable function (dubbed the Zap Gun Dual Wield) and the Quantum Entanglement Device (QED), a new tactical grenade. The map also introduces the Phasing Zombies and Astronaut Zombies and sees the return of the Crawler Zombies and Hellhounds. The map also introduces a new Perk-a-Cola called Mule Kick and two new pieces of equipment called the P.E.S. and the Hacker. The map does not feature any traps, but does have a new utility: the Launch Pad. There is also a major Easter Egg in this map, referred to as Richtofen's Grand Scheme, which helps Richtofen gain control of the zombies.