Gamasutra, the gaming industry's major publication, runs a feature article on the rise of alternate (or augmented) reality games and their potential for advertising. The most recent successful ARG was I Love Bees, created to promote the release of Microsoft's Halo 2 game.
In the article, Adrian Hon writes: "In terms of bang for buck, "I Love Bees" was exceptionally cost effective in gaining international media attention for Halo 2, and demonstrated perfectly how the viral nature of ARGs allows them to attract large audiences with comparatively small outlay, and just as importantly, create a rich and compelling "alternate reality" storyline. The fact that ARGs are entertainment themselves also gives them a way to appeal to communities that are otherwise very sensitive or neglected by traditional marketing campaigns. When EA spends over $100 million per quarter on marketing and even then finds it hard to penetrate some communities, using innovative techniques such as ARGs to appeal to large audiences can save potentially save millions. "