World of Warcraft expansion hit by server bugs
World of Warcraft subscribers are suffering crashes and long waits to start playing after its new expansion pack became the latest video game to suffer computer server faults.
These included making servers in Europe unavailable for nearly five hours on Saturday to upgrade the hardware.
One company watcher said it was surprising given Blizzard's experience.
Warlords of Draenor - which went on sale on Thursday - is the fifth expansion to WoW's 10-year-old fantasy role-playing game. It provides access to a new orc-controlled planet, called Draenor.
"While the majority of our players are able to play, we're very sorry that many are stuck in queues before they're able to get in, due to a combination of demand and the mitigating measures we've taken," a spokesman for Blizzard told the BBC.
"We've been working around the clock to upgrade hardware as well as implement further software solutions so that we can reduce the queues to get in, and we've already seen considerable improvement."
Other titles currently experiencing server problems include Microsoft's sci-fi shooter, Halo: The Master Chief Collection, which also went on sale last week.
Its developer, 343 Industries, has acknowledged "frustrating" bugs with its Matchmaking system, which links players together over the internet for multiplayer battles. The firm delayed the launch of an associated e-sports league as a result.
"We're working around the clock, alongside the Xbox Live team, to improve the situation," a Microsoft spokesman told the BBC.
"This is our top priority and will keep everyone updated regularly via Halo Waypoint."
Sony's multiplayer racing game Driveclub also continues to suffer connectivity problems more than a month after it went on sale. Evolution, the studio behind the title, announced on Friday that it would give away content as compensation.
"If you release a product into retail, it's expected to work - it's basic retail etiquette," commented James Batchelor, editor of games industry magazine Develop.
"I don't think [server problems] damage day-one sales, but it does damage a publisher's reputation.
"EA still has this kind of stigma after Sim City, which was over a year ago, because of the fact that it took it so long to get that game working."
Crashes and lag
Problems affecting the update to WoW were exacerbated by a distributed denial of services (DDoS) attack, which flooded Blizzard's computers with internet traffic last week.
However, the US-based company acknowledges it has struggled with unexpectedly high peaks in the number of people trying to log in.
As a consequence, common complaints include "realms" going offline, or there being large queues to join one.
Realms are different copies of WoW's fantasy universe, each containing the same content but different characters. Each is hosted by a different set of computer servers.
At the time of writing, nine of the game's 266 realms were down and 24 were "full".
Blizzard said that to improve stability it had cut the number of players that could be active in each realm simultaneously, causing log-in delays.
- "Player not found" error messages, preventing players connecting to the game
- Blocked access to dungeons
- Characters getting stuck while making use of Garrison zones - a new feature that provides users with a fortress where they can manage their operations
- In-game lag - in highly populated areas some actions are delayed and certain enemies attack prematurely
Blizzard said a number of hardware and software fixes meant it had been able to start raising the maximum number of players in each realm.
But it added that it required "additional oversight and testing" to ensure other planned fixes, including adding more servers, did not introduce further problems.
Despite a succession of video game launches struck by similar issues, one expert was surprised to see World of Warcraft struggle.
"You would expect Blizzard to have a huge amount of experience managing the load on the number of servers it has," said Piers Harding-Rolls, head of games at the consultancy IHS.
"It has dealt with bigger amounts of users in the past."
He added that if the main cause of the problem was indeed higher demand than expected, that could prove fruitful if the firm fixed the problems fast enough.
Blizzard announced WoW had 7.4 million subscribers in October - down from a peak of 12 million in 2010, but an improvement on August's figure of 6.8 million.
Mr Harding-Rolls added that the firm had faced a tricky "balancing act" when deciding how much server infrastructure to provide.
"When a new piece of content comes onto the market you have to anticipate what kind of demand there will be and at what time of the day people will be using it.
"It's not an exact science. If you haven't got the assumptions right you don't get the best result.
"And you have to do it in a commercial way, avoiding ploughing too much into the infrastructure and then not regaining the investment you've made."