NeverLost

The NeverLost resembles a belt with a pda-sized computer and several lenses mounted on it. When worn, it captures a 360o image of your location once a second. By comparing sequential images, it forms a three-dimensional model of your location.

(If the necessary calculations cannot be performed by a portable chip, the device can instead save the images and wirelessly transmit them to a central internet server when in range.)

By 'walking through' the generated model on the device's screen, the user can perfectly see the spatial connections between any two places they have visited that day. By zooming out, they can get a god's-eye view of their travels. The NeverLost will at last entirely eliminate the perils of becoming lost in foreign cities, shopping malls, trackless forests and etc.

At the end of the day, the maps can be conveted into the format of a popular multiplayer shooting game, and you can fight it out amongst the places that you visited that day.