I would love to see like the game being possibly darker at nights, and that you have to build a generator for which you have to find some fuel that could be pretty rare, because they could maybe turn the power off after couple of days.
I also think that water from sinks would also rock, but it would be too easy so maybe something like powered sinks (from the generator) with finite water?
edit: I forgot that some (toggleable) night raids on PC home would be fun, maybe also some barricades for doors and windows.
love your work btw, i hope that you wont overwork.
btw there are 8 unpainted pixels in the main menu by the road xD