Orbster's GPS Mission is a web- and smartphone-based map game that's now being offered as a free iPhone app. Brags the makers:
"This multiplayer scavenger hunt game will take you to the most interesting places around — for free. Explore your world in a completely new and playful way using your GPS-enabled phone. Enter the community to show where you've been and what missions you've solved. Create your own missions and challenge other players!"
Even more significant, the coders have opted to use the Open Street Map project, rather than the better-known Google Maps, as OSM is not only user-supported (and thereby more readily updated), but also has better coverage in such atypical locales as Eastern Europe, South Africa and Australia, as well as a greater selection of footpaths for non-automotive navigation.
[Available from iTunes]