Using real landmarks
Location-based mixed-reality games (also referred to as pervasive games) are worth dedicating at least a chapter to, if not a whole book. It is a new and now massively popular class of online entertainment. The concept is simple. Some objectives, events, or items in a game are connected to specific GPS coordinates on a real map. Usually, such a marker is attached to a city or natural landmark in a game to better express it. The introduction of such games was only a matter of time, since they act as handy virtual maps and reliable algorithms of navigation. Sooner or later, it was obvious that developers would implement this in a game.
The general feature of location-based games is the real-world map scaled down for gaming—the story takes place in the physical world; as once stated by one of the characters from Lewis Carroll's books, "We now use the country itself, as its own map". Quests are set in real city streets so players have to step outside...