On the occasion of today's fourth birthday of Duke Nukem 3D (story), newly opened PlanetDuke has posted an interview with George Broussard, top-Duke at 3D Realms. George recalls his memories of the shareware release and how things took off from there, and looks ahead at the fourth installment in the series, Duke Nukem Forever. Here is a quote on the latter topic:

There are a ton of folks that are worried that Duke won't be Duke because you went to an engine that had no embedded ability to play with stuff. Give us some hints about interactivity -- can we play games within games? Pick stuff up? Move stuff around??

We spent most of our early programming efforts modifying and extending Unreal so it can handle an interactive game like Duke Forever. I can say with relative certainty that Duke Forever will be the most interactive FPS to date. Bar none. If something exists in the world you will be able to do something with it in some way. The game will reward the player for using items and exploring. Without going into too much specific detail, let's just say that the stuff you mentioned above could be the tip of the iceberg.