slickrcbd: I really hate this trend of calling demos anything but a demo. Labeling a "prologue" or "chapter 1" or "the beginning". Why can't they mark demos as demos?
lupineshadow: I'd be happy with the term "shareware" too :)
Quake Episode 1 ticks all the boxes of the description of a prologue above...and was shareware.
Similarly Duke Nukem 3D.
If I remember correctly, both named games included all resource files, just part of the content was locked.
In the case of Quake it was a setup file, that would change the games .exe
That's not what "prologues" and so one are, these are separated programs. so they are closer to a demo than to a shareware product.
There even existed an id-Soft shareware CD which you could buy in stores. For the unlock codes you had to call id-Soft and pay.