As Electronic Arts prepares to release its heavily publicized, subscription-based online game Star Wars: The Old Republic, market analysis firm Newzoo has released new data showing science fiction and space-themed MMOs are dominated by free-to-play games.

Sci-fi and space massively multiplayer online games (MMOs) are played by an estimated 14 million people in the U.S., according to Newzoo’s 2011 MMO Report, but a full 68 percent say they only play free-to-play MMOs, with half of the remainder saying they play some mix of free and subscription-based games.

The ratios are similar in Europe, where 76 percent of sci-fi MMO players ignore subscription games, and in the emerging markets of Brazil, Mexico and Russia, where 80 percent of sci-fi MMO players play exclusively for free, Newzoo said. Paid subscription MMOs fare somewhat better in Asia, where 52 percent of sci-fi MMO players pay for at least one subscription.

Newzoo’s report comes as more and more MMOs transition to a free-to-play model as a way to attract players, who may eventually pay much more for in-game items. Warner Bros.’ DC Universe Online saw its revenues increase 700 percent following a recent move to a free model, and even venerable subscription-based MMO World of Warcraft recently expanded its free trial to allow unlimited free play up through level 20. Last month, Newzoo estimated total U.S. spending on all free-to-play titles has increased 24 percent in 2011.

EA is bucking this trend by charging upwards of  $13 per month for access to The Old Republic, which is currently in beta and launches fully on December 20 . EA CEO John Riccitiello said in September that the game would need about half a million subscribers to break even, and the company says the beta test has currently attracted over 2 million players.

While Newzoo CEO Peter Warman said he didn’t want to use the MMO data to make any predictions about the fate of The Old Republic, he did say he was “very curious to see how [many free-to-play] sci-fi gamers EA will be able to convert to [paid subscription] gamers.” EA could also find success by converting subscribers from successful fantasy-themed MMOs, such as World of Warcraft and Rift, Warman said.