Since its release last Friday, thousands of players have struggled to untangle the knotty thicket of puzzles hidden deep within Xbox 360 indie title Fez, the 2D-meets-3D puzzle platformer that drove us batty with its obscure stumpers. Since then, only a few hundred have managed to complete enough of the game's challenges to reach the 200 percent (yes, 200 percent) completion threshold. That's an achievement in itself, but until Wednesday, none of those players had actually been able to complete the game's most difficult puzzle, which involves a black monolith floating inside a hidden underground chamber.

Actually, that's not strictly true—a small handful of people had unlocked the monolith's secrets. But those solvers had either stumbled onto the solution without knowing how they had done so, or else a source close to Fez developer Polytron had provided the answer. For the rest of the Fez-playing public, unlocking the secrets of the monolith became a project that took a concerted collaborative effort and nearly a full week of focused attention.

"Good luck with that."

When game designer Trey Reyher reached out for help with the monolith puzzle driving him up the wall, he contacted a friend who had worked on Fez. He received an disheartening reply: "Good luck with that. It's practically impossible."

Reyher had already discovered the first two pieces of a mysterious three-piece, heart-shaped block that didn't appear in the game's official inventory. He found the first piece by button mashing, which was a bit lucky. (The actual solution involves taking a blinking pattern shown by two tiny red dots and converting it first into binary and then into ASCII to get a six-button code.) The second piece Reyher had deciphered from a maddeningly cryptic "security question" hidden inside the game. But he despaired at ever finding the key that could unlock the third piece from that mysterious black monolith. Finally, he begged his friend from the game for help.

"I was given the solution," Reyher said. "I entered it and became, as far as I know, the first person off the development team to finish everything in the game."

But while Reyher had the code to unlock the monolith, he didn't understand where that code came from (aside from insider developer sources, that is). And he was sworn to secrecy in any case, so he and the Fez community at large still didn't have the closure they needed.

Translating the tome

The only in-game clue clearly tied to the monolith's solution was a "tome," a hard-to-find artifact that opened to reveal eight pages of text in the game's coded language. The cover of the tome matched a 3D symbol etched on the ground beneath the monolith, and players already knew how to translate the tome's mysterious symbols into an alphanumeric sequence, one that seemed to spell out complete gibberish. Beyond that, though, no one seemed to have any idea what it meant.

Peter Silk, a part-time game designer himself, was one of the many players who had swept through most of Fez over its launch weekend. He too got hopelessly stuck on the monolith. He attacked the problem methodically, taking pen and paper notes on the tome to try and unlock its secret meaning. Silk spent a full day staring at his notes, wondering how to convert the book's gibberish into something comprehensible. Finally, he gave up and logged into the GameFAQs forums, expecting to find the solution already posted. He was almost pleased to see everyone else just as lost as he was.

By this point, Polytron had mischievously tweeted its faux unawareness of any black monolith. A few hours later, Reyher uploaded a picture of his completed heart block, obtained through insider info. The picture spread across forum threads on sites like GameFAQs, NeoGAF, and Xbox 360 Achievements. All were filled with players desperately hunting for the solution just days after the game's release.

"Some people had done some clever work already, such as frequency analysis of the letters to show that they were just out of order and not substituted," Silk told Ars. "But people just didn't seem to know where to go from there."

Then Silk had a brainstorm. He realized the 3D symbol on the cover of the tome might relate to the order in which its pages should be read. "Perhaps it needed to be read three dimensionally—not just going page by page but reading through letters in a certain sequence of pages," Silk recalls thinking. "The problem is that there are so many ways to do that."

To try and get a handle on how to traverse the tome's pages, Silk recalled something he'd read in Simon Singh's The Code Book: codebreakers use educated guesses to give themselves a starting point. He slept on that thought, and as he was leaving for work the next day he realized what his starting point would be: "hexahedron."