Full list of files:
I will start giving some detailed information about the episodes and maps. Later I will explain the rest.
The folders labeled "EPISODE#" basically holds the maps for the game. The files are much bigger than the default *.map format from the PC version. I assume the *.pmp extension stands for "[P-word] map".
As you can see, there are 5 episodes. However, the 5th holds the maps in Duke-match mode. Except for the first map, all others are copies of maps from other episodes.
Episode 5 is called Butt Kicking Zone in Auto-map, and here is the list of levels: Quirk of Fate, Hollywood Holocaust, Launch Facility, L.A. Rumble, Raw Meat, Red Light District, Lunatic Fringe, Death Row, Spaceport, Faces of Death. For some reason I don't understand the files in episode 5 aren't exactly the same size as their respective replicas in other folders, despite them being virtually identical in-game.
E1L9 is a scrapped map called "Blank" which also uses an unusued track. The map is just a small untextured C-shapped room (notice the file size is very small). Other than that, HUD and menu fonts are all screwed, and other default game behaviors are malfunctioning (i.e. gravity).
The folder "DEMO" simply contains 4 Demo files.
The folder "CINEMA" contains various *.srt files, which are essentially all movies. These can be easily converted using softwares available on the Internet.
The *.XA files in the main directory constains the music files. These also can be converted using softwares available on the Internet. However it would be even better to download the musics from composer website. As you can see there are 3 *.WAV left in the CD-ROM.
The folder "FILLERS" constains blank files with *.BIN extension. I assume, as the name suggest, they were meant to fill the remaining space. Probably the same also applies to the *.PAD files in the main directory.
So after I explained what everything else is, now comes the key files.
SYSTEM is just a default Windows shortcut and it contains a few DOS-like command lines.
Finally SLUS_003.55 appear to be the most important file, in HEX the header is labeled "PS-X EXE". Other than that you can see in HEX the text strings from menu and quotes (in case of an European release requires translation). The quotes from USER.CON are there but nothing special, as you may expect there is no string for Expander or whatsoever.
What bothers me is that SLUS_003.55 is only 600kb. While the CON codes in v1.3D are merely 161kb, the executable alone should be worth over 1mb. Not to mention the various art and misc files in the GRP. Which raises the question of where that content is stored?
As I mentioned before, the *.pmp map files are much bigger than the original *.map files. However E1L1 is only 1.6mb and I am not sure if all the HUD, menu and misc would be just that (for comparison, the Shareware version GRP is 10mb, while the full 1.3D version is 25mb, giving the Shareware version over twice the average size per map).
Eliminating all other possibilities, it appear that the art and misc can only be held in the *.map files. But as I mentioned before, I find it strange based on the size of the map files.