The ARG became famous as a promotional tool for companies to leverage advertising in a transmedia world. It was an exciting way of getting better word of mouth marketing and interest into a new product. The most notable ARG’s are The Beast and I Love Bees for Spielberg’s “A.I.” and Halo 2 respectively.
As part of a marketing drive for both these products, the publishing companies behind them developed intricate ARG’s to get people more interested and invested in the product. And this was done through deciphering codes on websites, finding hidden locations, delivering items to dead-drops, listening to audio recordings, and so forth, the list goes on. But the main thing is that these games didn’t rely purely on the format that the product came in. The Beast did not purely exist in the film world, it was everywhere, so anyone could join.
Other examples are ARG’s developed for “Cloverfield”, “Super 8”, “Tron: Legacy” and much more. A more recent one that people may be familiar with is Blizzard’s ARG for the Sombra character in that was released in 2016 for Overwatch.
TV series such as “Supernatural” and “Dexter” have also dabbled in ARG’s.
Many of these ARG’s incorporated breadcrumbs/clue games and geolocation techniques to leverage a worldwide audience. They are also some of the first games to widely use QR and Barcode technology, due to its ease and visually cryptic look.
Many of these ARG’s were quite successful with a great number of people enjoying them. They all finished, either due to the game running its course or in some unfortunate cases, because the financing ran out. But many participants still remember them fondly because they seemed so very real.