K, There are these things called "headcrabs" from half life 2, little alien crab things that latch onto your head
Have a team helping you and the headcrabs latch onto the players and it is shown as such, then you must kill the "headcrab zombies" and the headcrabs.
If you have ever played half life 2 you know what this is and stuff.
There is a spawn that the headcrabs come from
The zombies walk pretty slow probably just a little slower than normal speed (If normal scale is 1.0, they probably go about 0.85)
To set up the game have a certain amount of bots on your side of the team, Then headcrabs will spawn, and you have to kill all the headcrab zombies. And you win! But if everyone (the real players "humans" playing bl NOT Bots) has a headcrab aattached to them, then the humans loose D:
I have a picture below as sort of a reference, i might post what a headcrab looks like and a zombie.
Please make :D (please dont think of this as the zombie mod and make them kill bricks, They dont kill bricks, they follow you and kill you D:)\
Ok i have a headcrab, i did not get the zombie because all the pictures would scare little kidos :P They are pretty creepy when you get down to them with the rotting flesh and all...
So basicly this little guy just like sits on top of its host's head :D