I just saw your post and link, and the dirt path looks pretty cool!

However, the dirt paths might look weird with the surrounding qr codes and such...so maybe somewhere in your town we can create dirt paths in a small area? Or do you want your whole town to have dirt paths? Also, are you sure you want to do this? I like the idea, but if we do the dirt paths and you change your mind then it might be hard to recover the grass XD.