okay, good idea on the whole clicking thing, but I don't see the reason for me to give myself a disadvantage when I can easily just use drones and keep clicking on the zombie and do pretty much nothing.
what I'm saying is, this game is set int he most easiest mode possible to the point where there is no challenge or a way the lose other than clicking to spawn a zombie and not shoot.
I know what you are trying to make, but it seems that you want a lack of any challenge while also having a form of challenge.