From the release:
MEIN ZOMBIE™ is a flexible and expandable 1:1rule system for recreating the massive Zombie infection. Designed to be used with miniature scales from 15 up to 28mm, it is based around our innovative Drop-ln TM game system. Players from novice to veteran will find it easy to customize the game to their particular gaming style.
This player-friendly approach to war gaming builds around solid and easily leaned basic rules, which present an excellent balance of playability and historical accuracy. Once you quickly lean the core rules, you simply "drop in" additional rule modules as you see fit Each Drop-In utilize the same terms and mechanics for entirely seamless integration into a full featured game system.