The game lacks the traditional "acts" of a zombie setting. There are hints of it, I guess; the national guard week, and eventually the "'Aaahem-, *Clowns* -hem'" show up, and the undead do get gradually tougher. Outside of this, it's rather uniform.
Ideally, you'd have at least one "normal" day, where most people don't know about the Zombie Threat and the electricity is working. After that you have the mob day, where there's still few zombies, but everybody's panicking as the true nature of the plauge reveals itself, then you have the rest of the first week, with the gradual build up, and then you get the first appearance of the National Guard and some martial law...
It's also lacking the stunned civilians- that is, not the survivors, but the civilians who just try to hide out on the roofs and are still clutching their briefcases and memos, knowing that if they just hide out long enough, the powers that be will save them and bring the world back to normal.
Here's a thought; after the Nat'l Guard retreats, remaining troops would be a kind of remnant force, and would presumably lack some of the dicipline of the regulars, possibly scavaging and hunting much like the bikers and gangers.
You know, one thing I haven't seen a lot of in Zombie settings is cults. You'd expect that there's got to be a few religious folk who would take the entirely scientific and secular phenomenon of a zombie uprising entirely the wrong way and believe it to be some kind of divine judgement. Besides, who wouldn't want to hear something like "You hear the sound of distant chanting! The Zoonies have arrived! Cultists seem to be coming from 168 tiles to the NE!"
Now, Tahin and I where considering that rather than a virus, a fungal infection could behave more like the Zombie Plague- for one thing, the human immune system has a lot of trouble with fungi, and it could provide more energy than whatever it is that powers regular zombies.
I'm not saying that it's a good idea for you to use Fungal Zombies. I'm just saying it allowed us to have a gang of zombie-smoking hippies.
I'm all for the nausea meter and pink bottles. You could make it so some zombies smell terrible, or that an unskilled combatant exposed to gore could get effected in a realistic way. Also, don't go down in the sewers on a full stomach.
Oh, and if you spend too much time in the dark, you could get cave-adapted!
Nah.