'Round and 'round we go...
In response to Gearbox Software filing a Complaint against 3D Realms and Interceptor for unauthorized use of the Duke Nukem trademark, 3D Realms (along with Defendants Apogee Software and Interceptor Entertainment) submitted an Answer on March 18, 2014. It's mostly boilerplate, with the Defendants denying or claiming insufficient information to the majority of paragraphs -- the stuff that makes up most Answers.
However, it gets interesting when 3D Realms asserts its affirmative defenses. 3D Realms states that in the Asset Purchase Agreement that was executed to transfer the rights of Duke Nukem Forever, that 3D Realms was entitled to complete and sell a videogame called "Duke Nukem Survivor." This is apparently the Duke Nukem: Mass Destruction game that is the subject of this matter.
Further, 3D Realms says that Gearbox doesn't own the Duke Nukem trademark anyway, as it was never part of the Asset Purchase Agreement. As the Answer puts it "The Duke Nukem trademark rights remain the sole property of 3DR."