Multiple problems with Polymer combined with the general disdain shown to the HRP put a lot of modellers off. Trying to make modern assets with ancient model formats and tools and a broken renderer put paid to the Duke modelling scene. Polymer, when it all works well, looks great. Making content for it though is a huge pain in the ass.
A lot of the pre-polymer models were jumbled into the later HRP along with polymer-made assets. A lot of the older models looked their age and didn't fit in with the newer assets. No attempt was made to adjust the appearance of the older models under polymer and they wound up looking like they were made of latex. The mix of old and new was jarring.
On a more positive note, as far as I know, Roma Loom and others have been plugging away at the wall and floor/ceiling textures for years now and last I looked, they were of a high standard.
Before Serious Duke3d, there was a Duke BFG by Kaffeebohnson, where most of the monsters from DNF were ported over to work in SS3.
https://steamcommuni...es/?appid=41070
After that, there was a mod where you could play SS3 as the character of Duke. The results were amazing. Duke fit right in as if the game was made for him. Pan, Batandy, Viper45 Sedinus and Noam 2000 all contributed to this version.
https://youtu.be/8DCq_NQ4oOY
There is a link to the steam workshop page on the Youtube link.
Serious Duke3d was mostly made by Syndroid. I provided some props, vehicles and the pig cop tank. I don't know if he asked permission for the assets in the HRP. As far as I know, he authored the levels all by himself. This recreated the first episode of Duke Nukem 3D by putting all the parts together in the SS3 Fusion engine.
After he made the first episode of Duke3D in SS3, the plan was to do something new and original, taking Duke3D off into new territory. I haven't heard from him in a while, so I don't know what is going on or what is planned further for the project.
Now, imagine if the Duke modelling community hadn't evaporated. There could have been people to help create levels for SS3, to adjust the behaviour code of monsters to more closely match a Duke game. More props, new monsters, new levels and stories. Gearbox isn't going to make a new Duke game? The community used to be chock-full of talent and enthusiasm. We could have made our own. That's all gone now.
There could have been, now that we know it's possible, a project to make a new fan-made Duke game on a modern engine. That isn't happening, and probably is now unlikely to happen, as the modelling community all disappeared years ago. That's a shame.