"Supposedly, it was set up for auto-pay, just like any other bill in real life, but either that didn't happen or the money wasn't in the wallet, and then everything just escalated out of control from there," said Carl, who lives in Costa Mesa, California. "The dust is still settling on that issue. Everyone is just focused right now on fighting to try to regain control of the system."

During Monday's encounter, more than 100 Titan vessels were destroyed. The megaships, which are akin to the Death Star from Star Wars, are the largest ships in the game and are worth about $US3000 each in real-world money. The Titans also take months for gamers to build. That's months in real time: a lot of nights, weekends and days-off actually spent constructing the virtual warships.

Carl was awakened by a messaging app on his phone used by alliance members alerting him that their system B-R5RB was under attack by rivals. He wasn't scheduled to work in real life on Monday, so he spent the entire day sending virtual ships into the fray. He said dozens of his alliance members took off work to join the fight, which is being waged by more than 4000 players - and watched by thousands more on the game streaming service Twitch.

It's an unprecedented battle unique to EVE, which simulates a universe of more than 7000 stars and whose virtual economy is linked to real-world money, unlike many other online role-playing games, such as World of Warcraft and Lord of the Rings Online.

"I'd be lying if I said our servers weren't sweating a bit," said EVE Online spokesman Ned Coker of CCP Games, the Iceland-based video game developer who created the online universe. "Allowing players free movement wherever they want in a game with over half a million players means for some pretty tricky technological requirements."