Star Wars: The Old Republic launched and lets gamers play as characters from the iconic SF series.
Reputed to have cost more than $130m (£87m) to develop, SWTOR is a bid to grab a chunk of the lucrative gaming market for publisher EA.
It faces stiff competition from established titles, such as World of Warcraft, and many free-to-play games.
The Old Republic is set 3,500 years before the events depicted in the Star Wars films but uses many familiar elements from the movies.
Many aspects of the game involve moral choices that push players towards the light and the dark sides of the force.
The Old Republic (SWTOR) is a massively multi-player online (MMO) game and resembles World of Warcraft (WoW) and many others in that it asks players to go adventuring to turn their relatively weak starting character into a powerful hero.
Players can choose to play as many different races including human, Sith pureblood, Twi'lek and cyborg. At the start of the game players must choose whether to be part of the Galactic Republic or Sith Empire.
Continue reading the main story
“Start Quote Playing dark side, you can do some horrible things, which is fantastic”
Rock Paper Shotgun
Different species adventure as one of several different classes including Jedi knights, smugglers, troopers and bounty hunters. Players also get a starship to explore the many different planets making up the SWTOR galaxy.
The game went on sale in the US and Europe but people who pre-ordered the game got access from as early as 13 December.
In the UK, the basic edition costs £45 and this includes the first month of online play. Continuing to play requires payment of an £8.99 monthly fee.
Other editions, deluxe and collectors, are available and include items for use in the game as well as a security module to help prevent an account from being stolen.
John Walker, a journalist at PC games news site Rock Paper Shotgun, gave a cautious welcome to the game. He said it was an "interesting confusion" of WoW and classic PC game Knights of the Old Republic.
Mr Walker said visually the game resembled a smartened up WoW and borrowed many of the well-known mechanics from that and other online role-playing games.