while im pretty sure the devs have a least a rough draft of some enemy types, here is my shtick.
amputee zombies - missing arms or legs and what not. kinda slow but hey if something is crawling towards you and is missing its lower half your still probably gonna s*** your pants.
infected animals - like common birds and dogs
non-infected humans - what happens after a major natural disaster looting? right? gangs take the streets and loot the area and they dont take too kindly to strangers on their turf. basically like modern day bandits, but not all are like that some may have gone insane like the Quislings in WWZ
the basic zombie - enough said
screamers - can alert the other zombies in the area making it abit more hard, given the chance of being surrounded.
sprinting zombies - the name says it all.
hulking zombies - increased strength and look like infected body builders
my girlfriend - enough said
vomiting zombie - can blur the vision of the player
weapon using zombies - just the basics melee weapons, its not like the smart zombie like in the day of the dead movie
well thats all i got!
(A really infected dog)
