Here is a version of the Dynamic Zombie Sandbox which first appeared for ARMA 2, OA, and CO, and now has been ported to ARMA 3.

Download Link: http://dynamiczombiesandbox.com/downloads/
Forum Link: http://forums.bistudio.com/showthread.php?147599-Mission-Dynamic-Zombie-Sandbox-Arma-3

If you know how to extract .PBO's, and repack them you can edit the parameters which are found in the description.ext file.