As the campaign continues, you and the zombies will reach progress milestones. Your milestones make the game easier, while the zombies tend to make the game more challenging.
Each milestone is marked on the victory track, making it easy to tell how close you are to an event.
|700||Research Labs||Scientists begin to appear, and collecting them allows you to increase technology.|
|1200||Catbird Cannon||The catbird cannon charges as you evacuate civilians, or kill zombies. Each use will carpet a small area with explosives.|
|2000||Elephantbird Cannon||About once every year, you get to use the Elephantbird cannon. It's a powerful version of your artillery, and can conquer the greatest infestations with ease.|
|2600||Llama bomb||About once every year, you et to use Llama bombs. It clears out groups of territories from the zombie infestation. If you remove all zombies, you get extra scientists, but the zombies return next month.|
|3500||Big Bad Zeppelin||Your zeppelin carries one additional mercenary.|
|500||Heavy Infestation||Zombies outbreaks are level 2.|
|1200||Gas Ruptures||Gas lines have ruptured in some buildings. If destroyed, they cause a large explosion.|
|2500||Zed Mutates||Some missions will have large zombies, that can only be destroyed by explosives.|