Is the zombie faction playable? Yes, it is! It is called "The Contagion".
How does the zombie-infection spread? When an infection building appears it reduces ALL farming output in the region, tax rate and the amount of trade in the region. Hordes of zombies will begin to appear in the region and the population begins to turn into zombies. The outbreak is contained by demolishing the infection building and killing all the zombies.
To defend against the epidemic declare martial law for territories adjacent to zombie virus outbreaks. Your territory will incur a penalty with reduced tax collection and trade. The increase in the law public order will dramatically reduce the chances of catching the zombie virus from a 100 percent change of infection to a manageable 5 percent chance. How do I test this new mod? 1) Your must have Rome: Total War - Alexander
3) Unpack the file directly to the Rome Total War folder (the folder with RomeTW.exe and RomeTW-ALX.exe)
4) To start Rome: Total War - Zombie Mod run the file Zombie Mod.bat in the Rome Total War folder.
5) Attention!
a. Every time you start a new campaign or load a saved game you have to select your city.
b. Click the face of the advisor on the left-top of the screen. The advisor will say that the Main campaign script has been activated. [Playing without the main script activated is pointless because the script controls the spread of the zombie infection.]