@Frank...
...but Zombies are like star wars.
The good and the bad are clearly defined.
And this is the reason why games with zombies, werewolfs, vampires, the peronal evil always works. You simply can´t get enough from the question ... how can you kill somebody who is already dead. It is strange to shoot on soldiers in cod, but it is mysterious to shot on something which humanity can´t explain.
This is the stuff since the beginning of mankind. The fear of the dark, the fear of the dead, fear of hell, fear of pain... suffering... death.

...fight your inner fear...
in games... with balls and great weapons. This is legal and wanted.