The Dark Knight ARG was an alternate reality game created by Warner Bros. and 42 Entertainment to promote The Dark Knight, the second Batman movie directed by Christopher Nolan. Unlike most online games, an ARG includes an immersive storyline the players are characters in; in the case of The Dark Knight, all players are citizens of the fictional Gotham City. An ARG requires searching for clues to continue the story on the Internet, on the phone, and at real-life events. Activities in the Dark Knight game included:
- Going to bakeries and picking up cakes with cell phones in them
- Decoding messages on official theater posters
- Submitting images of people wearing Joker makeup
- Using clues from other websites to turn in corrupt police officers
Once an objective in the game was completed, all participants were rewarded with new TDK promotional material, such as trailers, pictures from the movie, and posters. Those who participated outside of the Internet received items like newspapers, clown masks and cell phones.
 The story
The ARG timeline presumably begins immediately after the conclusion of Batman Begins, when Lieutenant James Gordon tells Batman about the existence of a theatrical murderous criminal who calls himself the Joker.
Since Gotham City DA Carl Finch was killed during the timeline of Batman Begins, Roger Garcetti is elected to act as DA. Along with Rachel Dawes, a new hotshot lawyer named Harvey Dent makes up the prosecution team as Assistant District Attorney. Dent immediately begins work to clean up police corruption in the city, inspiring Gotham citizens to make the website Ibelieveinharveydent.com in May 2007.
A mysterious figure makes his own site mocking the Dent support, deforming the image of Harvey Dent at Ibelieveinharveydenttoo.com. By inviting online participants to submit their emails, he gradually revealed himself on the site as the Joker. When this was done, he erased everything on the page save an encoded message: "See you in December."
In July, the Joker emerges again at the San Diego Comic Con looking for recruits to cause public havoc. A massive scavenger hunt across the city begins as a mob wearing clown makeup, working with friends online, wanders across San Diego and wreaks havoc according to the Joker's directions. The game ends when someone standing in for the Joker is driven away by possible gangsters, who kill him shortly after. The Gotham authorities believe that the threat is eliminated, but the Joker assures his followers that he is alive and well.
On Halloween, the Joker prepares a new recruitment game by having hopefuls look for prominently displayed letters on buildings across America to discover his motto: "The only sensible way to live in this world is without rules." He then encourages participants to take group photos of themselves dressed like him in public, for his amusement.
As a reward for playing the game, the Joker sends all the participants a copy of The Gotham Times. In it, the reader learns about the growing mob war in Gotham, Harvey Dent's actions to curb police corruption, and Batman's ambivalent place in Gotham society. In the newspaper itself, the Joker publicized a recruitment email address in a classified ad, and makes a parody website of the newspaper at Thehahahatimes.com.
By submitting tips to Harvey Dent's police corruption website, the participant becomes privy to a sting operation involving two police officers who are then caught in the act of accepting bribes. The operation goes wrong and a shoot-out occurs, in which one of the accused officers die. In the interrogation of the surviving officer afterwards, it is clear that Gotham police officers feel threatened by Harvey Dent's actions to crack down on corruption, as well as the pressure of working in such a crime-ridden city.
In the meantime, the Joker is once again making his presence known throughout Gotham, inviting participants into more games via the email address that he publicized in the newspaper. The games culminate in December, in a final recruitment exercise in the guise of a carnival game, which whittles down the field to 22 recruits on the ground carrying cell phones, awaiting the Joker's future orders. He invites all other hopefuls to "meet him," keeping his promise of seeing them in December.
As the Gotham City elections in June approach, the support for Harvey Dent escalate at Ibelieveinharveydent.com. Dent himself calls each one of his supporters asking them for help to get him elected as Gotham DA. Fellow supporters are asked to spread the word by giving away campaign materials and submitting photos and video of themselves campaigning.
They are rewarded with copies of a new issue of The Gotham Times. In it, Harvey Dent officially announces his candidacy for Gotham District Attorney, opposing Roger Garcetti (who plays dirty politics) and Dana Worthington. In addition, there are yet more articles about the ongoing mob war, various GPD mob-related investigations, and the cumulative effect of such violence on Gotham citizens, even including widows of the involved mobsters. There are also updates to events that have occurred between the two issues. Batman has found some ardent support among civilians, and Karl Breitup's death resonates within his family as well as his company. Finally, it is clear that the events that took place in Batman Begins have not faded in time - Arkham Asylum is under fire and many inmates who escaped the asylum during the Narrows Attack have never been found. Still, most of the focus is on the upcoming race for Gotham DA.
Not long after, a huge bombshell is dropped: a group calling itself Concerned Citizens for a Better Gotham releases testimony from GPD officers that Harvey Dent bribed and blackmailed them into testifying against innocent cops. However, not all is what it seems. The founder of CCFABG.org seems to have shady ties of his own, possibly connected to the police as the corruption in Gotham's police department seems to run deeper. On his campaign website, Roger Garcetti calls for Dent's withdrawal from the race due to allegations that he bribed decorated GPD officer Francis Notaro to falsely testify against his fellow officers. Dent denies all allegations, but his support is waning. Even though a few familiar believers still stand by him despite the negative attacks, moves have been made to prevent their voices from being heard.
Amid the political mudslinging, owners of the Joker cell phones are contacted and given "secret letters." This led to a new recruitment exercise on April Fool's Day that involves the retrieval of bowling balls and cell phones from bowling alleys across the world. Once all were found, the Joker asked his minions to hack into the website of the ACME security company. But this proved to be a trap: Jim Gordon proceeded to call those who attempted to hack into the system and told them they must help the police or face jail time.
In Dent's defense, an investigation into the Notaro allegations began, which implicates Joseph Candoloro (the founder of Ccfabg.org), Albert Rossi (a deli owner with criminal ties) and the mob, Francis Notaro, the GPD and Garcetti's DA office in the cover-up in the murder of a possibly innocent man, in which Notaro received the Gotham Medal of Commendation for supposedly killing a dangerous criminal. A soon-to-be-published Notaro interview with Times reporter James Levine threatens to blow the top off of the whole affair. In fear of Internal Affairs as well as the mob, Notaro makes plans to leave Gotham with his family. But after his partner Cisneros and his family are killed in a car bombing, Notaro snaps and takes hostages at Rossi's Deli, causing a Harvey Dent campaign press conference to be canceled due to the police response. Before the situation can elevate into something worse, Harvey Dent enters the building and successfully convinces Notaro to let the hostages go and surrender to the police. Having nothing else to lose, Notaro tells the police about the mob's involvement in the anti-Harvey Dent smear campaign.
With Concerned Citizens for a Better Gotham now exposed as a mob operation, Joseph Candoloro (under the command of a unidentified person known only as "Iceman") orders all officers involved to leave Gotham. In response, Jim Gordon launches "Operation Slipknot" to catch them before they can leave the city. The ex-Joker henchmen caught via the ACME sting are told to intercept care packages Candoloro is sending the dirty cops at the Gotham Intercontinental Hotel to try and find out where they are going. Thanks to their efforts, 27 of the 30 missing officers are arrested. The combination of the end of the smear campaign and the Rossi's Deli incident cause Harvey Dent's poll numbers to rebound. However, the Joker, having a currently unknown connection to the sting, was able to use the contents of the care packages to organize rallies for his minions in 12 cities.
A new Gotham news site reports on the popularity of Harvey Dent after the successful negotiation that ended the Notaro hostage situation. Still, the crime rate is increasing in the city partially thanks to the ongoing mob war, and there has been some public backlash against the neighborhood watchdog group inspired by Batman.
Meanwhile, Citizens for Batman is fracturing. Despite the efforts of the moderator for the group's message board to ensure the organization's goals are only to support Batman and set up neighborhood watch programs, many of its members are leaving the group so they can take the law into their own hands.
As city-wide voting gets underway, the Joker clues in his followers that he might once again emerge on Friday the 13th. Once the polls are closed, Harvey Dent wins by a landslide. His first act as District Attorney is to charge Roger Garcetti with criminal charges related to his connections with mob boss Sal Maroni.
Voters are rewarded for their participation in the election with a new issue of The Gotham Times. Harvey Dent makes the front page with his historic win, but it is Batman who makes the headlines after a proposition that would have helped prevent his arrest fails at the polls. The city is becoming increasingly ill-equipped to fight the Fear Toxin, and the Joker's cake hunt has led to the closing of several bakeries after it was found that the cakes were poisoned. Citizens of Batman is under fire from the GPD for allegedly harboring vigilantes, though group leader Brian Douglass denies the charge.
Shortly after the election, the Joker gives word that the Gotham City Pizzeria will give away free pizzas across the country, obstensibly to promote the chain. But the pizza boxes also contain notes that, when pieced together, reveal a hidden forum on the Citizens for Batman website, unauthorized and not known about by its leaders, where some of its former members are planning to emulate Batman and become vigilantes. Shortly after the promotion is over, the Joker uses the pizzeria's own website to hint that Harvey Dent may not be all he claims to be.
As Gotham Cable News continue to inform its viewers about events in the city, including Operation Slipknot's catching of two of the three missing corrupt cops and the revelation that Roger Garcetti was the "Iceman" who organized Concerned Citizens for a Better Gotham, the Joker continues to make himself known in the city's underworld. Leaving messages to his followers in the form of carnival games, he first reveals that he was behind the theft of a large supply of ammonium nitrate capable of making numerous bombs, then declares that he masterminded the death of two of Sal Maroni's goons, an incident which could rekindle the gang war.
In reaction to the defeat of Proposition D ("Save Batman") at the polls, members of Citizens for Batman begin to use various means at their disposal to increase support for Batman. This culminates with the announcement of pro-Batman rallies, although these events were nearly cancelled thanks to a setback. At these events, CFB supporters project Batman's insignia onto prominent buildings. But their true intentions may be far different: Brian Douglass himself has become a vigilante and led the group on their first crime-fighting run.
Shortly after these meetings, the Joker launches an all-out assault on law and order in the city, first vandalizing nearly every website in Gotham and then stealing 68 million dollars from the Gotham National Bank in a robbery that leaves five of his henchmen dead. The story then continues in The Dark Knight.
 How to participate
There are currently no opportunities to participate in the game at this time. It can be assumed from the Joker's checklist that all trails in the game have closed and the ARG is over.