Call of Duty Zombies has experimented with numerous concepts over the years. While some attempts at trying something fresh do not work out, such as what was seen with Call of Duty: Vanguard Zombies, other tries to innovate result in mechanics that become integral to the foundation of Zombies. The craftable items and more complex map design seen in Black Ops 2 are just a few examples of a new idea working out and becoming something that is expected from future maps.