The maps are kinda low res, but as far as I can tell, the two city maps seem to be largely hand-drawn, maybe with the coloring done in Photoshop. Unless you've got a firm sketching hand, and a bit of knowledge on PS (or Gimp), you're probably not going to get something that looks like this. The world map looks far simpler, could probably be done in Gimp with the right brush pack and some simple coloring.