[In this complete and comprehensive article, Rob Jagnow of Lazy 8 Studios (developers of Cogs) take you behind the scenes of the Portal 2 ARG which lead up to the early release of Valve's highly-anticipated sequel.]

Way back in March of 2010, Valve added a mysterious new achievement to Portal. In no time at all, players figured out that if they carried the in-game radios to specific locations within each level, they could change the radio transmission. In the parlance of Alternate Reality Games (ARGs), this is referred to as a "rabbit hole" -- a point of entry into a much deeper universe.

From the crackling radio transmissions, players managed to decode embedded images. One clue led to the next to the next, sending players on a massive scavenger hunt that included dialing into an old-school BBS and retrieving cryptic ASCII images, culminating in the announcement that a sequel to the popular game was in the works.

The puzzles were challenging, but the whole sequence, from beginning to end, only took the community of players a few hours to solve.

Project Timeline

Fast-forward to December, 2010. Following the success of the prior ARG, members of the Portal 2 team suggest that they'd like to do something similar in the lead-up to launch; only this time, they'd like to wrangle the creative talents of some of the indie developers with popular Steam titles.

The next day, an invitation goes out; a week later, on December 16, 2010, 20 indie developers fly in to Seattle, all somewhat confused as to why they are there in the first place.

With everyone gathered in Valve's sixth-floor fishbowl conference room, Gabe Himself lays out the core idea: Somehow use our Steam games to usher in the arrival of Portal 2. That's it. There's no agenda and no grand plan. Just pack a room full of fun, creative people and give them unrestricted access to Valve's resources, including Portal 2 assets. No constraints. No NDAs. This was a project built on trust and mutual respect.

During our two days at Valve, we formulated the minimalist story that we would use to drive the event: GLaDOS has infiltrated our games and she slowly makes herself visible as she seeks to make her comeback. New content will be added to the games in three phases, starting with only vague mysteries and working up to GLaDOS making an explicit appearance. To make it easier for hard-core fans to participate in every aspect of the ARG, we plan to release all of the participating games for 75 percent off in a bundle called The Potato Sack.

We schedule enough time between the content releases to allow players to solve the puzzles and to give the media time to pick up the story. The event is designed to culminate with the crescendo, in which players will spend time in each of the participating games to roll back the Portal 2 launch clock.

ARG Philosophy

The Portal 2 ARG is a great example of Valve's philosophy of digital distribution: let's give new value to our old games in a way that engages our existing fans and draws in new ones. This philosophy sets Steam apart from other portals, where content updates are difficult, if not impossible.

I suspect that the ARG converted quite a few pirates to legitimate customers. If they want to have access to the new content and participate in the metagame, they'll need to own the game, and have an authenticated connection with the Steam servers.

Everyone wins. Valve draws attention to the Portal 2 launch. Indie developers, who don't have the benefit of a multi-million-dollar marketing budget, draw attention to their titles and benefit from the Potato Sack sales. Old fans get hundreds of hours of new content in their favorite indie games, plus a metagame built on top of it all. New players get all of this, wrapped up in a package discounted by 75 percent.

Developer Coordination

To help the teams coordinate from our offices spread across multiple continents and time zones, Valve set up a secure wiki where we could share our ideas and critical information that was needed by all of the teams. This is where many of the game and metastructure puzzles were formed. In addition, we had a high-traffic internal mailing list that hit around 150 messages a day during the height of the ARG.

There were no conference calls and no IRC chats. Other than the meeting in December 2010, the only time we all met in person was during a March 10 meeting in Seattle where we finalized our plans and made sure everyone was on the same page for the April 1st #PotatoFoolsDay launch.

ARG Metastructure

Jeep Barnett at Valve spearheaded the ARG metastructure by combining ideas from the wiki into a mega puzzle and breaking it into components that could be spread across all the games. The first revision was completed on February 3.

Phase 1. April 1, 2011, every developer will release new content tagged in the update notes with #PotatoFoolsDay. Hidden somewhere in each game will be a glyph with a consonant equivalent and a nonsense sentence with exactly 16 consonants. Taken together, this data can be used to create 13 images with the letters "COLLABORATION" -- a password that will be needed in Phase 2.

Phase 2. April 7, games are patched with subtle clues that may be construed as being related to Portal 2. Each game also has a hidden password and an action that players can perform to open an Aperture Science login page. If the player enters the correct password from another game, a .zip file is transferred to their computer.

Inside the .zip files are Portal 2 concept art. Hidden in the alpha channel of the images are black-and-white photographs of real-world Seattle locations that will need to be connected together in Phase 3. Also in the .zip files are data chunks that can be sewn together into a larger .zip file, password protected with the previously collected password, "COLLABORATION". Inside is even more great concept art and other Seattle locations.

Phase 3. On April 12, games are updated yet again. This time, GLaDOS makes prominent appearances and the ARG community really starts to pick up. Each game has one or more actions that can be performed to open an Aperture Science page where GLaDOS speaks a peculiar sentence that references two of the aforementioned Seattle locations.

When the locations are connected together accordingly, they spell out the word "nelipot". This, in turn, is the name of a Steam group where users can find some Portal 2 screenshots and a QR code that points them to the [email protected] page and thus the start of the crescendo.

Crescendo. Originally scheduled for April 16 or 17, the crescendo was designed to give players an opportunity to play all of the participating games to chop time off of the Portal 2 launch clock. In a last-minute decision, we decided to move up the start of the crescendo to give more time for international fans to participate and also to give more time for the media to key in to the event. In retrospect, this was a bad decision. I'll discuss this later.

Launch. Based on the efforts of the players, Portal 2 launched at 9:29pm on Monday, April 18 -- nine and a half hours earlier than the originally scheduled Tuesday morning launch.

The ARG metastructure ended up working well for both designers and players. For the designers, we had a roadmap of where to go, but the constraints were loose, so we were free to pursue puzzle ideas that are suitable for our own games and consistent with the Portal 2 fiction as well as the fiction of our own game universe.

This resulted in an astonishing variety of challenges, including story that spanned far beyond the metastruture requirements. For instance, the Dejobaan team had an expansive collection of blogs, tweets and videos that revolved around a whole new set of fictional characters with clues that tied loosely back into the main ARG.

For the fans, being able to piece together the metastructure limited the space they needed to explore and helped save them from pursuing too many red herrings. For instance, once it became clear that in Phase 1, each game contained one glyph and one nonsense sentence (something that was further hinted at by a brief image in one the Cave Johnson promotional videos), the players were able to focus their efforts on games where they had not yet found the clues.

One potential drawback to the weak constraints of the metastructure is that it didn't encourage the developers to collectively advance a strong fiction alongside the ARG puzzles. In hindsight, the ARG players seemed happy to have such a huge variety of puzzles and were very forgiving of the weak fiction. Rather than filling in a back story of GLaDOS, we chose to make her a commentator within most of our games, mocking the player in her characteristic style.