When they're chasing you the best option for a player is to immediately run back and past the zombie but what if you made the zombie tackle them and/or try and pull them and/or run into them?
Sweet! now we can all die! ;D
Make fat ones that are bulky against melee, waddle after you.
Super skinny ones, harder to kill with small bullets.
Those who're turning, or you could... make players turn? oh sweet...
I'm the kinda person that likes to see lots of variety of enemies, not always the same one or it can get a liiiiittle bit old...
Make them be capable of crawling through windows, broken gaps (such as a concrete wall players prone under), smashing a door open over time. (basicly just opening a door but loudly ;P not smashing it to pieces )
