a very convincing palette to achieve a dark feeling... it's quite difficult to criticise it because it might be just a matter of personal taste, but i think that, even if these colors create a particular feel, when i see them together they become a bit too gaudy to me. here's a little edit on the zombie, i tried to keep colors as vivid as you did (and probably more than as you did XD this saturation hurts)

i do love the green you used on it, but believe it doesn't fit greatly with such a creature and with the other characters...
you could also change the little folks' skin, choosing a different tone for highlights. desaturating could help, but i imagined you wouldn't be enthusiastic to use it, and that you'd rather keep them as they are to preserve that particular atmosphere. but i'd use it.