In a statement, creators Rajat and Jayant Agarwalla said they agreed to block Scrabulous in the United States and Canada in deference to Facebook's concerns, while continuing to pursue their legal defense. Rajat Agarwalla, describing the measures as "unfortunate," declined further comment.
Facebook said the Agarwalla brothers, not the company, made the decision.
In the year since Facebook began letting outside developers write Web programs that Facebook members can plug into their personal profile pages, Scrabulous has become one of the most popular applications, despite efforts by Scrabble's owners to end it.
Earlier this month, video game maker Electronic Arts Inc. released an official version for American and Canadian Facebook users under a licensing deal with Hasbro. But the authorized Scrabble has been attracting only 15,000 daily users, compared with some half-million for Scrabulous. That authorized version is actually still in a "beta" test mode, and encountered technical problems Tuesday.
After EA's release, Hasbro sued the Agarwalla brothers and their company in U.S. District Court in New York, accusing them of violating Hasbro's copyright and trademarks. The lawsuit seeks an end to Scrabulous and unspecified damages.
Facebook users who tried to access Scrabulous on Tuesday were simply told the game was disabled "until further notice," and many Facebook users updated their one-line status messages on the site to mourn the suspension.
Laura Chefer, an Atlanta Facebook user who logs on about 20 times a day to check on Scrabulous, said she had no sympathy for Hasbro despite its rights to the game.
"I was definitely shocked and annoyed," she said. "These two guys went to all the trouble to make this interface, and now the big company is suing them, and we're no longer able to play."
The game continues to work at the developers' Web site, Scrabulous.com, but users must sign up and start games afresh.