Potato Sack

The Potato Sack is the name of an alternate reality game (ARG) created by the Valve Corporation and the developers of thirteen independent video games to promote the release of Valve's title, Portal 2, in April 2011. Valve president Gabe Newell envisioned the game as a "Cross Game Design Event" in December 2010, and allowed the developers a free rein to design the game using Valve's Portal intellectual property. The game, requiring players to find and solve a number of puzzles hidden within updates of the thirteen games, ultimately led to the opportunity for players to release Portal 2 about 10 hours earlier than its planned release by playing games under the pretense of powering up GLaDOS, the sentient computer antagonist from Portal 2. The ARG's theme of potatoes is based on plot elements within Portal 2, specifically that for part of the game, GLaDOS's personality module is run off a potato battery.

Large numbers of people participated in solving the puzzles within the ARG. Reaction from players and journalists was mixed; some saw the ARG as a show of strong support and commitment by Valve for independent game development, while others thought the ultimate conclusion was of limited benefit to justify buying the games to begin with.

The ARG began without announcement with the release of the "Potato Sack Bundle" on Steam on April 1, 2011, which offered the included games at 75% off their normal price. The games included in the Potato Sack are listed below with their developer and release year.

On the release date of the Potato Sack bundle, players found the games within it had recently received updates. Most provided an immediate cosmetic change by replacing or adding assets that referred to potatoes. When players started looking deeper into these new assets, they discovered a series of glyphs that referred to other games associated with specific letters, as well as nonsense sentences that lead to specific cyphers. Other hints were less direct, using online services such as Twitter and YouTube to embed clues. In the case of Toki Tori, sections of new levels included braille code that referred to latitude and longitude coordinates of Two Tribes' headquarters. One player, "Jake_R", traveled to Two Tribes, where he discovered the glyphs and cyphers posted outside their headquarters. Several of Two Tribes' developers, upon learning of his presence, began filming him from a barbershop across the street. They would later use this footage of him climbing a pole to find these clues as part of another clue during the second phase.

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