I really enjoyed this - I like how it how that community (alone/together) feel, picking up notes from previous players to guide what to do. It'd be a lot of work, but if the city could be randomly-generated (or, at least, a bunch of different cities so a single player wouldn't get the same one twice) then that could really bump up the awesomeness of leaving notes. Either way, that concept was really cool. It was cool to see how much of the town was mapped before I got there, and the joy of finding a building that no-one had mapped before (but then dying because there were zombies inside and from the other buildings I'd been in I didn't think zombies could enter them, ha...)