You'll never set foot in Perplex City—not in person, and not even in a video game. You've been tasked with solving the mystery of a valuable cube that was stolen and secreted on Earth, but you can't visit the City to look for clues: All of your intel comes from studying blogs and websites, sending e-mail to fictional characters, and most of all, solving the puzzle cards that you buy on your way to beating more than 33,000 other players who are also on the hunt—and who all want the (real) $200,000 prize money.
The puzzle cards provide the meat of the game. Each carefully designed card tests your knowledge of statistics, cryptography, rock bands, Texas Hold 'Em, and English cookies. The easy ones take a few minutes or a Google search to solve, while the toughest stick you with a pair of GPS coordinates and some cryptic photos, and make you figure out what to do with them. Perplex City, which launched in the UK in 2004 but only recently came to the States, would make a fun trading-card game. But the cards are meant to pull you into the deeper story, where an alien city, a cast of characters, and a series of murders become more and more real the longer you obsess over them.
Beyond the game: You can also score points at live events, where hundreds of players have searched for clues on ferris wheels or in gigantic conga lines. The first American event takes place this August 12, in San Francisco.
Worth playing for: After you solve a card, you collect your points on the official website and claw your way up the leaderboards, where you're competing against—or collaborating with—a worldwide community of players. (At press time, the fourth-ranked player hails from Antarctica.)
Frustration sets in when: With 256 cards that sell in packs of six, plus duplicates, you'll spend plenty of cash keeping up.
Final judgment: This alternate-reality game presents an intriguing spin on life on the web: As we spend more of our lives online, it's as easy to immerse yourself in a make-believe world as a real one.