/vr/ - Retro Games

>>4986757
>and given how more than a few of the .wads contained rips from copyrighted materials, it was all kinds of shady and illegal
It was straight up declared illegal in 1998.
https://en.wikipedia.org/wiki/Micro_Star_v._FormGen_Inc..

Essentially, fan maps are the equivalent of licensed sequels to the original game, and thus cannot be sold unless given explicit permission from the rights holder.

"Therefore, it claims, nothing of Duke Nukem 3D's is reproduced in the [user made custom maps]. In making this argument, Micro Star misconstrues the protected work. The work that Micro Star infringes is the Duke Nukem 3D story itself--a beefy commando type named Duke who wanders around post-Apocalypse Los Angeles, shooting Pig Cops with a gun, lobbing hand grenades, searching for medkits and steroids, using a jetpack to leap over obstacles, blowing up gas tanks, avoiding radioactive slime. A copyright owner holds the right to create sequels... and the stories told in the [user maps] are surely sequels, telling new (though somewhat repetitive) tales of Duke's fabulous adventures."

~United States Court of Appeals, Ninth Circuit (1998)