More options on the custom game settings to blacklist and modify both more infected units as well as CERC units, also settings for victory conditions. Similar to how the Juggernaut, Leviathan, and Ravens can be turned off or adjusted, toggle and slider settings for Chelsea, the LT's, infected structures, and all CERC units could be added.
It would be cool to be able to set it all way down to basic infantry (or even police) versus basic zombies, with victory conditions for total annihilation, or to be able set it as high as all infected units against limited resources CERC response, being able to blacklist any CERC units that have infinite ammo like ammo tents, towers, turrets, etc.