Duke Nukem Forever was released in 2011 and it was a disaster, especially in graphics. If a sample of chain-link fence in Duke Nukem Forever looks like this:
And from 2004 DOOM 3 fence looks like this:
No matter how much DOOM 3 picture is downsized, u can see the difference in quality. Both games are made for scripted tube runs in tight 3d spaces, but only Duke Nukem Forever looks older than DOOM 3. 3D Realms has always been second/poorer version of id Software. Both worked together somehow, shared technology(?), but 3D Realms was always left with an old and worn technology.
In 1992 id Software brought us Wolfenstein 3D and was published by Apogee Software, which is 3D Realms. Then Apogee brought us Blake Stone: Aliens of Gold (1993), which is practically Wolfenstein 3D, or uses same technology. Then id released DOOM in 1993, which ate Blake Stone. Duke Nukem 3D came out in 1996, but id Software brought Quake in 1996, which is full 3d, while Duke 3D is not pure 3d, and uses old engine called Build. In 1997 3D Realms released Shadow Warrior which is practically Duke Nukem 3D with a new mask. This is where 3D Realms is totally lost and tries to keep up with technology for Duke Nukem Forever, constantly changing technology to new engine, while id Software maintains it stable production with fresh technology.