"This is a case about illegal free riding on recognized and valuable intellectual property rights," Zynga said in a lawsuit filed this week in California district court.
"'Bang With Friends' is a a completely anonymous way to hook up with your Facebook friends," according to the app description. The company says it has more than one million registered users.
Zynga, which owns "Words With Friends," "Hanging With Friends," and "Chess With Friends," said the company tried to informally approach BWF to discuss a name change, but talks did not lead to any change.
BWF, Zynga said, chose the "With Friends" moniker "to leverage and deliberately trade on the fame of Zynga's 'With Friends' family of marks in order to get noticed quickly in the sea of Internet applications."