Idea inspired by this thread: (background, we play on a small campus with lots of woods around us)
Day One Mission: Humans have to build a fort in the woods. It will be complete for the mission when the walls are X feet high. The size of the fort is up to the players. This fort will then be used the rest of the week as "base-camp" for the humans to create a real survival-esque atmosphere. They would be able to improve the fort throughout the week. Game mechanics could be implemented where at least 1 human has to be in the fort at all times during play (we have quiet hours from midnight-6am). Humans could create guard shifts and such.
Zeds could not touch the walls, but could perhaps breach the entrance if left open.
Just a rough idea I had. Thoughts/suggestions?
I like this idea, you could use it as trading post of some sorts as well