Welcome to competitive slow-gaming. Enable GPS and roam the Earth. Grid Walking will mark squares visited automatically. Visit 3 squares, get the 4th free and upgrade to a larger square. How large a square can you get? Visit bonus areas to get bonus points you can use to long-press-select the impossible-to-reach squares and mark them visited. Choose wisely, though, as bonus points are a scarce resource! Grid Walking uses the OpenStreetMap-Tool "osmdroid" for maps. Osmdroid is released under