So here's a thing somebody taught me about zombies. The guy was kinda short, and I think he had a third eye, but that's not important right now - this is what he told me.
There are three reasons that people have a healthy fear of zombies.
1. They represent 'disease'. Massive epidemics that whipe out entire continents if given half a chance. Usually, in zombie franchises, you've only got a handfull of 'immune' characters, who can't be affected by what turns the dead into zombies in the first place - no guarantees for bititng, though. This is a fear that branches nicely from real life - think Ebola, Spanish flu, and (snicker) Mexican flu...oh, who am I kidding, the Mexican flu is jackshit.
2. They (sort of) represent overpopulation. Fun fact: we're all terrified of other people - all those slow, lumbering jackasses who should be thrown into a woodchipper if we had our way, right? No? Just me? Anyway, that's another thing - a lot of folks are scared that there're just entirely too many people...aaaand they're right. We should depopulize.
3. There's the whole 'brutality' thing going on. Zombies act like mindless killing machines. They want your brains, and God damn, they'll make complete assholes out of themselves to get it. They're basically mankind, with what keeps them alive ramped up to eleven - brutalness, bloodthirst, beastial behaviour, and violence. See: the Ragers, the Infected
Now, pay special attention to that last point folks, because that's where our story of whimsy, fantasm and gore begins!
Let's put a few facts together. First thing up, Zombies Scare The Crap Out Of People, for aforementioned reasons.
Second thing up, Human Savages Scare People. You know what I'm talking about - homeless people that chase you with sharpened bindlesticks, people who do stuff like... say, Columbine, to give a very risky answer, and our all-time favourite, cannibals. Humans are the other red meat.
Third and last, Humans Have A Very Rational, Deepseated Fear, Of The 'Human Savage' With A Working Mind Behind It - e.g Hannibal Lecter, Leatherface, Jigsaw. Intelligent Psychopaths That Want Nothing More Than To Really Ruin Your Shit.
So, if it isn't clear by now, my premise is as follows - you take your usual Zombie Virus, and you start the first infection. Probably, at least some 85% of the world will be infected, and the rest would be immune to the probably airborne virus.
But these aren't your average zombies. They're not shambling, brainhungry automatons, nor are they just very fast and jumpy brainhungry motherfuckers. See, this'm particular strain of zombies is a bit more cunning, a bit more clever, if you will.
Sure, your average zombie will know that where there's noise, there's humans, but let's take a look at, for example, the movie I Am Legend (no bitchin' 'bout the mangled ending plz). The Darkstalkers (or whatever-which-thing they were called) actively set traps for Will Smith's character, showing a level of intelligence I've personally not yet encounted in any other zombies. And if you've seen the director's cut, you know the big reveal - they're all kinda intelligent, they just wanted the girl that Will Smith's character vamp-napped back, and then they'll bugger off... after eating him.
So, the premise is, Zombie Apocalypse with the twist du jour
: intelligence and malevolence. There's active scheming and brain function going on behind (what remains of) their eyes, but they've just got the single goal of 'murder', and there's no human inhibition left - no morals, no regret, no compassion.