REDMOND -- Hundreds of people gathered here this morning for the annual Microsoft Puzzle Hunt, sizing up the competition and preparing to spend hours immersed a series of mind-bending brain-teasers.

But first they faced a more basic challenge.

"You can figure out how to find the number for Pizza Schmizza on your own," said Peter Sarrett, one of the organizers of this year's event, during the opening Puzzle Hunt orientation session. "If you can't," he joked, "it's going to be a long weekend for you guys."

Actually, it's going to be a long weekend for many of them anyway -- but also fun. Now in its 12th year, the annual event for Microsoft employees, alumni, friends and family has grown to a record 1,100 participants this year, in Redmond (pictured below) and the Bay Area, grouped into 100 teams of no more than a dozen people. The event started this morning and runs through the night, ending at 5 p.m. Sunday.

Competitors started arriving around 9 a.m. today, some carrying pillows, preparing for a long night of puzzle-solving in conference rooms around the Redmond campus. After getting a rundown on the rules and procedures at the Microsoft conference center, they were presented with their first puzzle, pictured at top. (If you think you know the answer, post it in the comments below.)

Other Microsoft puzzle events, such as the College Puzzle Challenge, are designed in part for recruiting or other secondary purposes. But Puzzle Hunt is purely for fun. Some teams, designated recreational, get access to clues when they need them.

But the hard-core puzzle solvers don't get clues, and they take the challenge very seriously. Entrepreneur and Puzzazz creator Roy Leban, a former Microsoft employee and one of Puzzle Hunt's founders, showed up this morning with a trunk full of reference books, such as a dictionary of symbols. He even brought a musical keyboard, just in case one of the puzzles requires it.

Leban is a member of the veteran Puzzle Hunt team "TLA," which modifies its name in the form of a recursive acronym to fit the Puzzle Hunt theme each year. This year it's a "Jeopardy" theme, so the team is calling itself "TLA Listens to Alex," a reference to Alex Trebek.

After solving the initial puzzle, and retrieving the resulting clue, TLA gathered in its designated conference room (pictured) and divided into smaller groups to take on different puzzles simultaneously. Every solution resulted in a word that they posted to a bulletin board on one side of the conference room.

As they worked through the puzzles on their computer screens and printouts, they exchanged exclamations that would have seemed completely random to anyone who didn't know what was going on.

"Oh! Get the order they were admitted to the union!"

"Is there a dog named Platinum somehow?"

"A cryptogram is overkill for this. It's gotta be something more simple."

"Oh, duh, there you go!"

"Don't forget, you guys, these are the easy ones."

Yes, with more than 60 puzzles to solve, they've got a long way to go, and a long night ahead of them. But as veteran puzzle-solvers, they've come prepared. Their meals are already ordered.