Sony's PlayStation network is 'returning gradually' after a three-day outage that hit eager online gamers as they unwrapped their new consoles on Christmas morning.
Microsoft's Xbox Live service, which also went down on Thursday, was back online yesterday, although the company reported problems with some functions later.
Credit for the disruptions was claimed on Twitter by a group of self-proclaimed hackers called Lizard Squad, or someone purporting to speak for the group. But many video game enthusiasts and other hacker groups quickly condemned their actions.
Even the notorious Kim Dotcom, a New Zealand-based online entrepreneur who has been accused of abetting internet piracy, got into the act by offering free vouchers for his online privacy service if the Lizard Squad would agree to restore the Xbox network.
A Lizard Squad account on Twitter appeared to credit Dotcom's offer for the partial restoration of the Xbox service. But exactly what happened is still unclear.
Neither Sony nor Microsoft would say what disrupted their networks and experts say it is difficult to trace the source of attacks or confirm claims of responsibility.
Sony Online Entertainment said on its website that its Playstation network was being restored.
Signs of trouble emerged earlier this month when someone using a Lizard Squad account on Twitter began threatening to disrupt gaming services at Christmas and then boasted of causing the outages on Thursday.
A person or group using the same name on Twitter took credit last August for similar attacks in which hackers overwhelmed company servers with a flood of internet traffic, disrupting the online gaming networks operated by Sony, Riot Games and other companies.
The same Twitter account was also used in August to make an apparently false report that a bomb was on an aircraft carrying a Sony executive.
So far there is no specific evidence to link the episodes with last month's malware attacks on Sony's film division. The current episode does not appear to have exposed any corporate or customer data, but one expert said the Lizard Squad group was capable of serious disruption.