More than 1,000 eSports players are taking part in the Major League Gaming Championships in Anaheim, which began Friday and run through Sunday, the Orange County Register reported.
The contestants don special headphones and face off in soundproof booths in games such as "StarCraft II," ''Call of Duty: Ghosts" and "Super Smash Bros. Melee." Their battle chatter is broadcast live and announcers provide the play-by-play.
They're playing for $150,000 in prize money. Some have practiced up to 12 hours a day.
Matthew Fink, 25, of Minneapolis was competing in the "StarCraft II" open bracket. Born without a spleen, he lost his legs and forearms to infection at an early age.
Because of the amputations, he is slower than some when using the computer mouse and keyboard but said the game's emphasis on strategy helps even the playing field.
"I'm a very competitive person, but I've always felt like I was at some sort of disadvantage at whatever activity I undertook," Fink told the Register. "'StarCraft' is a game about how fast you are, but only up to a certain point. Eventually it's no longer about how fast your fingers are but how fast your mind works."
About 1,500 people were expected to watch the main events at the Anaheim Convention Center, and more than 2 million from around the world were expected to watch online via Major League Gaming's free streaming site, MLG.tv.
"Our audience is 16- to 34-year-old guys tuning in from 175 countries on average, and what's fascinating is that they are watching for two to three hours at a time," league spokeswoman Katie Goldberg said.