Hence Roberta's vision of MoE, which she didn't even get to finish, according to an interview with Ken Williams
Oh its much more complicated than that, much more. Ken Williams doesn't even cut the surface. It's a tale of technical hangups, failures by Dynamix to bring out the game engine on time, delays caused by the lack of engine to build the game on (at the last minute they had to spend a long time building a new one from scratch). Plus a game that was going way outside of budget and time issues. A total change to the art style, and to accomodate higher polygons (so the graphics wouldn't be out of date in 1998). It went a year over the estimated release date.
They had to make an engine from scratch (thanks to dynamix), which cut into their developmental time to incorporate scripted events, better cutscenes, more bosses, battles, action sequences, etc (that they had planned), this meant at least two levels were cut.
Even Roberta claims in interviews that she was starting to get tired of working on it for that long, the initial prediction was to finish it in 2 years (not counting extra year of design ideas), it got pushed to 3. Had she gotten the engine that Dynamix was supposed to finish on time, she might have made it.
Ken Williams says Roberta took inspiration from Duke Nukem when designing the game, it very well might have ended up being Duke Nukem Forever!