I'd love if the Game developers make -rare- child zombies... AKA "Imps" and made them move fast like a feral, run close then scream/stun like a screamer, no real attack to speak of / extremely low hit point's , just being a crowd drawing nuisance that are hard to hit.
I envision them constantly on the move, they only are still when they stand upright to scream, an audible clue to their proximity, could be a creepy childlike giggle.
If this idea finds your support let the devs know at :