The Olympics of the video game world began with players from 58 countries marching through the Los Angeles Convention Centre waving their nations' flags.
Over the next four days, more than 400 gamers will compete at the 10th annual World Cyber Games Grand Final for more than £158,000 in prize money, as well as new gear.
"We're quite confident," said Johan "Face" Klasson, who will be representing Sweden while playing the first-person shooter Counter-Strike with his team.
"I think the strongest opponents this year will be the Ukrainian team, also known as Navi. They've been playing really well in tournaments all over the world. Those are the ones we have to look out for," he said.
Players who previously qualified at regional competitions held across the world are to face off in such games as Guitar Hero 5, Forza Motorsport 3, FIFA 10, Tekken 6 and Warcraft III.
The tournament-style match-ups are occurring along rows of monitors erected in a giant circular pattern inside a dimly-lit convention hall.
After the World Cyber Games launched in Seoul in 2001, the grand final has been held over the past 10 years in such cities as Singapore, San Francisco, Seattle, Monza, Italy; and Cologne, Germany.
Last year organisers said more than 82,000 spectators attended the event at the Century City New Convention and Exposition Centre in Chengdu, China.
"We wanted to come back to America to celebrate our 10th anniversary because it's the most important market in terms of entertainment," said Hyoung Seok Kim, president of the World Cyber Games. "It's the centre of entertainment. Many publishers and developers are located here and there's a good infrastructure. We don't have to worry about translation."
Mr Kim said he expected 40,000 at this year's grand final.