Thousands of gamers have been unable to access Guild Wars 2 on the day of launch after an overwhelming surge of new users.
The game went on sale on Tuesday after five years of development.
It is the follow-up to the massively successful Guild Wars, which was the first no-subscription premium online RPG when it launched in 2005.
It is pitched as a next-generation online game which swaps drudgery for complex combat and story-telling.
Early reviewers have hailed the game's fresh take on the genre - despite its at-times baffling UI, controls and story-lines.
"It looks like madness," said <>a href="http://www.rockpapershotgun.com/2012/08/27/impressions-levels-1-15-in-guild-wars-2/">Rock Paper Shotgun, succinctly. "Anyone watching would think it a parody of a videogame, mindless button-pushing as endless flashing lights go off and a barrage of numbers pummels the monitor. "
The new game - set 250 years later on the fantasy world of Tyria- was hugely anticipated, and a 'pre-release' launch of 25 August was so popular it left many unable to access the game.
More than 400,000 people were playing the game at one time over the Bank Holiday weekend- even though it was only officially launched on Tuesday morning.
Now the game is publicly available - and, predictably, another surge of users has left its servers reeling.
"We are aware of some conectivity issues within the EU region," the game's developers said. "Please bear with us while our team looks into the problem."
But users were still unhappy:
Even those who logged in early to access the game have been left with long waits.
Other RPG and online games have also experienced delays soon after launch, including Diablo III, which left players locked out for hours at a time due to a post-launch surge in traffic.
Meanwhile other MMOs, such as Star Wars: The Old Republic, have experienced drops in users and revenue. Some games - including the Star Wars title - have since opted to go 'free to play' in order to attract new users.