I will see what kind of system I do when I get to that point. Just going with MapNav might be easiest. I'd have to create something which calculates a grid on the spot though, using whatever data is available on the world. MapNav in its current state is more geared towards creating the grid map at edit time. That would not be an option for a game where you want a piece of grid anywhere in the world. Creating one huge MapNav for the whole world is not an option either.