Well Grand Theft Auto V has a beta Hunt I feel GTA IV should as well. I will start by posting what i have found:
All images above were taken from "zombie.wtd"
It looks like GTA IV originally was supposed to have a zombie gamemode called "Angry & Hungry Resurrection"
Next I have a old Wanted Star from the beta period of the game
This is especially Interesting as you can see the wanted star is a classic Police badge in the beta. Its also strange That "Dance" is a blank, useless circle Texture and also that both are stored inside a file called: "level_design.wtd" as you can see on the top of the image.
Post your findings below and Happy Hunting!