Good point about the colours/lighting of the roofs. I did the roof colour before I added the building shadows, and didn't think much about lighting effects when I was colouring the roofs, obviously.

Given the building shadows, the light is coming from top-right, which would mean the three little buildings at bottom left are OK, but all the rest need tweaking.

Working on a larger-scale town/city map now, and thankfully bigger maps are a bit more forgiving of lighting effects - no shadows, for starters!