So you have tried to escape the town, shot up loads of Zombies from the original game but are looking for more.
Here it is Zombies 2, Zombie Corp.
This adds the military base to the core game and brings in more cards and super zombies, also allows you to move faster if you can find a jeep.
You get 15 more tiles to build the base up with, 30 new event cards I think these are better than the originals, 6 super zombies that glow in the dark.
Remember you do need the first Zombies game to play this.
Add it to the original game and lock & load.