Man, 26 years. Seriously? Ok, well, I better deal with it. I've told the story several times before about how much fun we three had making the first Keen games (me, Tom and John). Here's something that I've never talked about before.
In early January 1992, before we decided to make Wolfenstein 3D, we planned on making the third Commander Keen trilogy, "The Universe Is Toast!". This is the VGA parallaxing technology demo that used VGA versions of Keen 4's background texture. The project was actually seriously underway with entire directory hierarchy and 230 files in it before we decided to make Wolfenstein 3D instead.
The demo only shows one level that we made with parallaxing graphics. We only worked on this project for a couple weeks before switching to Wolfenstein 3D.