Needed some time to decompress after the MS Puzzle Hunt before I could go over it all again. For the curious, here's the set-up.
The hunt was announced via a letter to players, congratulating them on being accepted to the Time Corps-- a government research think tank established to exploit new Chronoscope technology that can peer backward through time. Time Corps is gathering the brightest historians, sociologists, and researchers to help analyze the mysteries of the past and create a better future.
Upon arrival the hunt, players are greeted by Chronoscope inventor and Time Corps founder Dr. Jacob Goode and given an orientation spiel about the Time Corps' history and mission, including a goofy call-and-response pledge (which, gratifyingly, the entire room of ~400 people played right along with). During that orientation, dissheveled and disgruntled researcher Dr. Richard Naste burst into the room demanding to know why he'd been locked out of his lab. The ensuing argument between Goode and Naste revealed that the Time Corps advisory board felt that Naste's research was dangerous and unethical, and that he'd been shut down and his credentials revoked. Naste, angry and egotistical, stormed out with a promise that this wasn't over. Teams were given their first set of puzzles-- "extracts" from the Chronoscope, each representing a particular period of time and named after historic events-- and dispersed to their separate conference rooms to begin working on them.
Five hours later, players were interrupted when their computers were taken over by a video message from Dr. Goode, informing them that Time Corps was in a state of security alert. Dangerous levels of chronoton emissions had been detected within the facility. All researchers were advised to don time-protective gear and proceed to the orientation area immediately for a security update. Players were warned this was not a drill and urged not to panic. (We later heard from a number of teams who were just stunned at how their machines had been taken over by our video, and who just sat there when it finished asking each other "How did they DO that?")
When teams arrived at the orientation area, they were met by Dr. Naste-- now immaculately attired in a fine suit, and attended by a number of other men in suits. The Time Corps logo behind him was subtly changed-- the S was missing. Naste proceeded to give a status report on TimeCorp's progress in various outrageous schemes to get wealthy-- extracting all diamonds from South African diamond mines centuries before they'd be discovered; inventing the lightbulb and phonograph, selling the patents to Edison, inventing improved versions, driving Edison out of business, and reacquiring the patents for a song; and so forth. Naste lead the group in a chant of the corporate motto, "Time is Money," before giving them their next set of puzzles, another set of historic events. (The script for this was very funny, and the audience obligingly shouted out two questions we wanted asked without our having to resort to the shills we'd planted: Where's Dr. Goode? and What happened to Time Corps?)
When players returned to their conference rooms, they discovered that the Puzzle Hunt web site, which had previously been the Time Corps home page (with info about the campus, advisory board, and so on) had changed. It was now the TimeCorp home page, with completely different personnel and history described therein. This included a password-protected "supply center" link which players couldn't access.
A few hours later another video interrupted players. Dr. Goode, apparently on the run and hiding somewhere in the TimeCorp facility, explains what happened. He didn't really invent the Chronoscope-- he found it frozen in ice in Siberia. In the process of analyzing it and learning how to use it, they theorized that it was part of a time machine that had exploded and become fragmented throughout time. Dr. Naste became obsessed with reconstucting the whole device. That's what the argument at the orientation was about. Naste had no concern about safety or ethics, and the board shut him down. But too late-- he'd obviously succeeded, activated his device, traveled through time and changed history so that Time Corps never existed. But his changes had more far-reaching consequences, and altered many events throughout history. Worse, these ripples in the timestream were becoming waves, which were becoming tsunamis, which would eventually shread the fabric of space-time with devastating results. Goode was sending this message to the new Time Corps employees because their labs, like his own, had the heaviest temporal shielding and he hoped they'd remember the old time stream as he did. Goode needed the players to figure out a way to reverse what Naste had done.
Goode also gave players a new set of puzzles. There were a total of 17 puzzles in the first two groups. This final group also had 17 puzzles-- one for each event in the first 17. But although their titles were the same, and in many cases they even looked the same as the previous puzzles, they were in fact completely different. As Goode said, history had changed-- all of these historical events had been altered.
Later, the players were emailed a status report which had been filled out for them by Dr. Goode. This was the meta puzzle. Solving it using answers from the other puzzles guided players to an Xbox kiosk on the MS campus, which we'd modified. To access the kiosk, players had to enter a series of 10 codes on the Xbox (which the meta puzzle revealed to them). Once they did, the Xbox gave them a game of Tetris to play. After clearing 10 lines, the right side of the screen became another video of Dr. Goode (if the players stopped playing at this or any point, or lost the game, they got kicked back out and had to reenter to code). Goode told players that Naste had managed to track down all the pieces of the time machine that had been scattered through time, and players had to do the same-- assemble their own machine with spares from the TimeCorp supply lab, go back in time to yesterday, and stop Naste from ever activating his own time machine. To find out what parts they needed, they'd have to do what Naste did and find them scattered through time. One time machine part was visible somewhere in each time period they'd studied, either in the original or alternate timeline. Goode gave them a password to the TimeCorp supply center web page which had, until now, been unavailable to them. There, players found an inventory list of 40 parts (only 17 of which were "real"), and a "Time Machine Schematic" puzzle. Once players searched through the puzzles and found the 17 time machine parts and entered them into the schematic, they got a 17-digit number which broke down into a building, room number, door lock combination, and chamber number. Dr. Goode from the original timeline met players at that location, having been sent a message from his future self. In that chamber was the time machine, and behind a glass wall was Dr. Naste frantically preparing to activate it. Players removed a key part from the machine, causing the machine to explode (sending the pieces scattering throughout time, thus closing the temporal causality loop at the heart of the hunt) and winning the game.