Nice.
Just one suggestion from one reasonably versed in zombie gaming

skin tones.
There's no variety in your skin pallour, they all look freshly munched (granted that may be what you're going for) but I would suggest a mix of blue/purple/green washes, blended and watered down, just to give the skin some more depth/ sunken sockets etc. It would also help pick out the detail on a few that look a little heavily painted in the face department too. Also don't be afraid to add some grey, green, blue or purple paint into your fleshtones. All helps give the illusion of dead flesh.
Don't be afraid to play either, if it looks wrong, then just build on it.
Good luck
The Commander