Dave Walsh is a world-class killer. He has ended more lives than just about anyone on the planet, and this weekend in Vegas he's going to kill again. Here he comes now, entering a dark room filled with plasma screens and oily teens. Dressed in a black T-shirt and jeans, he sizes up the crowd, walking past models shilling for Dr Pepper and Stride gum, slowing when the glare of the camera lights hits him. That's when the screaming starts. No, "Walshy" isn't some adolescent psychopath. He's a 24-year-old hit man who banks more than $100,000 a year playing video games. Teens and parents alike ask him to sign their controllers, their shirts, even their body parts. "He's always been my role model," said a 15-year-old Wisconsin kid named Jared at a tournament last October in Dallas. "He started everything." Because Jared had nothing for Walshy to sign, he pressed him to autograph his forehead. When asked when he planned to wash the Sharpie stain from his brow, he said, "Hopefully never."

Yes, video games are blamed for everything from obesity to illiteracy, and yes, gamers spend absurd amounts of time in front of their monitors, but Walshy's no deadbeat. He was a two-sport athlete in high school (tennis and wrestling). He has a girlfriend and his choice of groupies, his own clothing line, his own charity, and a sponsorship deal with Red Bull. Until six years ago, he made his money by sorting mail 65 hours a week with his dad at a Grand Rapids, Michigan, post office. Growing up, he heard the usual "You're going to hurt your eyes staring at that screen!" from his mom, Mary, who is a nurse and a triathlete, but that didn't stop him from jumping into a buddy's car the moment he learned about a Halo tournament in Nashville. Halo, for the uninitiated, tests a gamer's ability to navigate a science-fiction world, gunning down enemy fighters to capture objects like flags and skulls. Walshy—known as a brilliant and fearless strategist—returned from that first tournament with $50. He kept driving, and winning, and soon he had a team and a sponsor. He won a Dodge Charger SRT8 and sold it to fund a clothing company. By 2004, he was the world's foremost Halo player and the star of Major League Gaming's fledgling pro circuit.

For Walshy, the road to perdition starts with the Claw. Instead of relying on his index finger to shoot, like everyone else, he uses his middle finger, which frees up his index finger to move his character more quickly. The index finger, poised on top of the controller, looks like a talon. Walshy's also an instinctive leader, which is pivotal in Halo matches, for which teams line up four-on-four on either side of a wall of monitors. Most pros rely on a coach who stands behind them barking instructions, but Walshy operates like a point guard, directing his teammates with his skipper, slowly maneuvering his opponents into position for a kill.