So, Atari continued to accept payments ("including future royalty payments") from Turbine for the Dungeons and Dragons Online "sublicense" though, Turbine alleges, Atari had a "strategy" to either "terminate Turbine as part of a shakedown" or "proceed with termination in bad faith to benefit from its own competing product at Turbine's expense." We can assume that "competing product" is Atari's upcoming Champions Online MMO, being developed by its recently acquired in-house MMO dev Cryptic Studios.
So, to recap: Atari wants to terminate the license agreement with Turbine to develop and maintain the Dungeons and Dragons Online MMO franchise, including the just-announced "Unlimited" free-to-play variant. Turbine says that such a termination threatens its "past investment" in the franchise and the "goodwill" it's developed with the DDO playerbase, and those they expect to play DDO Unlimited. And now, it's up to the courts!