I haven't used it, but I remember hearing about "Fog of World"[1], which seems like it might be what you're looking for. [1] https://itunes.apple.com/us/app/fo

I haven't used it, but I remember hearing about "Fog of World"[1], which seems like it might be what you're looking for. [1] https://itunes.apple.com/us/app/fog-of-world/id505367096?mt=8 https://itunes.apple.com/us/app/fog-of-world/id505367096?mt=...