Yeah, they are quite reminiscent of Duke II, especially the one with the skyscrapers in the letters. I was amazed at those early Shadow Warrior screenshots too.
A lot of stuff in there, it's too bad that some of the more interesting ones like DNF and Prey cannot be released. Duke Nukem Forever actually started life as a 2D platformer with prerendered backgrounds and sprites. Eventually, they sold the engine to some other company and they released a game I used to play a lot as a kid, Alien Rampage.
I think, my two holy grails would be Prey circa 1997-1998 and Duke Nukem Forever 2001. Prey was exhibited in E3 and there are a couple of videos out there with some nice stuff. Looked pretty cutting edge at the time.
http://www.youtube.com/watch?v=PcSp0CznRNk
http://www.youtube.com/watch?v=L29DSSQT3Ek
The DNF 2001 trailer was also amazing. I doubt the game could have ever been released and been as awesome as that trailer. It was just too good.
Of course, beggars can't be choosers, and we should always appreciate what we're getting. As such, I am very very greatful to the guys at Interceptor Software, they're being too nice with the fans.