3D Realms has dropped its lawsuit against Duke Nukem Forever co-creator Gearbox and apologised for any damage caused.

The company was suing Gearbox Software for what it claimed was US$2 million (NZ$2.5 million) in unpaid royalties and fees related to the widely-loathed 2011 FPS.

When the lawsuit surfaced in June, Gearbox said it was evidence Apogee was "unable to accept reality".

In a statement, 3D Realms CEO and founder Scott Miller confirmed that the lawsuit was over.

"After reviewing evidence regarding our business affairs, and without any money exchanging hands, we have satisfactorily resolved any and all differences that we perceived against Gearbox," said Miller.

"In all sincerity, we regret the misunderstanding that instigated our lawsuit. Now that we better understand – and appreciate – the actual nature of our business matters, we have voluntarily withdrawn our claims against Gearbox, with genuine apologies to Randy [Pitchford] for any damage that our lawsuit may have caused to the relationship."

Duke Nukem Forever took 12 years to complete, passing through the hands of several studios in that time.