Thanks for the comments Jupiter. We ran out of time, we had so many ideas to add to the game:
* Inventory System (I wanted a window based on where you could equip armor, select weapons and use medkits etc)
* More collectible items
* More weapons (shotgun, crossbow, 2x4 etc)
* Larger/More levels
* Different type of Zeds
* Human enemies
* Start/Stop sections of levels, forcing you to Clear (;)) before you can move on
* NPCs