I like that idea, so that way during the day we can explore and build barracades, without having to worry about zombies. Plus it seems realistic and that way you have things you need to worry about at night and during the day.
I also think that the stories should start off a little bit better. The Retro Mall story started off really vaguely and didn't mention anything about the zombies. Before starting a new story, the author should include a brief background about the story and some ground rules, like what zombie types will be used and why the goal is (survive for x number of days, get to safe house/pickup point/supply point, etc.)