Here's an older mockup of the set (not sure how much older, but the building shadows are done with tiles). I've thrown on the 20% navy blue filter so you can see what it would look like at night. It's not the prettiest solution, but it's something that can be accomplished easily for every possible case and still look good enough. Also, the dark building has dilapidated plaster and boarded up windows, but it was a test case - I've not even remotely done enough of it to convert an entire city. I'm not against replacing the green grass tiles with yellow grass tiles for the aftermath construction - that looks really good. The fog is something that would be done in a separate layer, like the doodads and shadows, so it's not really part of the tileset itself - but it is something I've considered, depending on what kind of performance hit it would require. Similarly, I'm thinking the shadows of a few clouds shifting across the landscape would look pretty good if I did it so that it didn't look stupid on buildings.
I'm fairly satisfied with the color usage. I'm going for a gray, overcast feel - a sense of foreboding and isolation. Remember, this is before the world ends - when the first zombie seen could still be mistaken for a drunkard. It has to feel evil, but otherwise seem like a world that is currently inhabited and taken care of. I think the colors I've selected works towards that goal. I do agree that the road colors are far too bright though. It's distracting. When you stare at the screen, the first thing you see are the crosswalks jumping out at you.
