Hasbro, based in Pawtucket, R.I., is suing RJ Softwares and two brothers who created the knockoff game, which draws 1 million players a day on Facebook, for copyright infringement, the New York Post newspaper reported Friday.
The lawsuit, filed in a federal court in New York, claims Scrabulous creators Jayant and Rajat Agarwalla "have conceded that (the game) is essentially an online version of Scrabble by stating, 'It's not really different.'"
Scrabulous allows Facebook's visitors to play what essentially is an online game of Scrabble. It is one of the social network site's most visited games.
A Facebook spokeswoman said the company's "hope and expectation is that the parties can resolve their disagreements in a manner that satisfies the parties, that continues to offer a great experience to gamers and that doesn't discourage other developers from using (Facebook) to share their creativity and test new ideas."
Hasbro said it waited until its own version of online Scrabble was running on Facebook before trying to take down the copycat, the Post said.