The Lost Experience
An Alternate Reality Game based on the TV show Lost, which ran during the break between Seasons 2 and 3. It delivered substantial amounts of information about the show's mythology, such as the purpose of the DHARMA Initiative and the meaning of the Numbers (4 8 15 16 23 42)*. It did so by telling the story of DHARMA's financing group, the Hanso Foundation, and a few rebels trying to expose its illicit activities.
The game was loosely divided into five stages. The first began with a Hanso Foundation ad during an episode of Lost, which led viewers to a phone number and website. Both of these, however, had been hacked by someone known only as Persephone. Over the next few weeks, Persephone placed numerous hidden games and clues around the Hanso Foundation website, revealing corruption in the highest ranks of the foundation. Soon, another major character appeared: DJ Dan, a conspiracy buff with his own underground podcast, who would discuss the Hanso Foundation for much of the run of the game, including two live call-in shows (callers appeared on earlier shows but those were clearly fake).
After many weeks of this, the Hanso Foundation discovered the hacks to their website and shut it down. This moved the game into the second phase, where Persephone's true identity was revealed: a young lady named Rachel Blake who had one blog describing her European vacation, and a secret blog that told the real reason she was in Europe- to get the scoop on the Hanso Foundation, particularly its current leader Thomas Mittelwerk, and its elusive founder Alvar Hanso. Video blogs followed her quest around Europe, tracking the movements of Mittelwerk. The third and most complicated phase was announced at Comic Con 2006, when Rachel Blake herself appeared during the Lost panel to chew out the creators of the show for allying themselves with the Hanso Foundation, and launched her new website, hansoexposed.com. On this website, viewers would enter codes from "glyphs" found in the real world, TV, or the web, and piece together another video from Rachel one bit at a time. This part included a new DHARMA orientation film that explained the purpose of the Initiative: during the Cold War, the UN decided to research a way to stop mankind from destroying itself. The result of that research was the Valenzetti Equation: a mathematical equation capable of predicting "the exact number of years and months until humanity extinguishes itself" via any number of factors: war, environmental catastrophe, etc. The purpose of the Initiative was to find a way to delay The End of the World as We Know It by, via scientific research, changing the "core factors" of the equation: the infamous Numbers. The video then cuts to one made by Rachel where Mittlewerk explains to a group of scientists that "the DHARMA Initiative failed" and reveals that he and the Foundation have switched to more extreme methods.
The next stage overlapped with the glyph stage- and this one had candy! Apollo Bars were given away at various events across the country, and players were invited to post pictures of themselves with the bars on the website "whereisalvar.com". Once enough people posted pictures, including several ones with "Golden Oracle" stickers on them, the stage was set for the finale- one last live DJ Dan show, and a video from Rachel in which she finally meets Alvar Hanso, who is revealed to be her long lost father.
A behind-the-scenes video is here.
Later Lost ARGs were the much less complicated, but much flashier, Find 815, and then a DHARMA story that got cancelled after stage one due to the economic recession. Lost University isn't strictly an ARG, as it doesn't pretend to be a "real" story, but it still is essentially the latest and presumably last of the series.