>>Separated by the physical location of both places (e.g. New York and Paris), but connected by the virtual link through a device like a palm-pilot, both players have access to the combined map. The mixture of physical and virtual obstacles have to be used tactically by both players and an specific buildings(e.g. phonebox) have additional effects on the game.<<

>>Using GPS and other mobile technology, Amalgam enables you to bring two real spaces together.<<

I mention this project in the Mixed Reality workshop.
The project is called AMALGAM, by Marcus Kirsch and Jeremy Gay (2002)

more info:
amalgam