How to autoload files
There is a way for modders/etc to "autoload" files into 3DGE:
Autoloading WADS with a shortcut
This is a good method to use if you want to play many mods for 3DGE that consist of multiple files. This is not technically autoloading (because you need to create a batch file). To do this, first create a shortcut to 3DGE.exe on the desktop, or anywhere that suits your needs. Then right-click on it, and go to “Properties”. In the “Link to...” box, by default you should see:
In this box, add the following commandline:
-file <file1> <file2> <file3> <file4> ...
And so on, replacing the example with the names of the files of your choice. Put a space between the filenames. For example, if you wanted to play a mod named doomhell.wad with additional patches coolweap.wad and newenemy.wad (yes, obviously the example lacks creativity), your command line should look like this:
C:\directory\3DGE.exe -file doomhell.wad coolweap.wad newenemy.wad
The -file parameter will assume that, if a filename is missing the extension, that file is a WAD file. Since the “Link to...” can only contain 255 characters, it is a good idea to omit the .WAD extensions when loading a very large number of files.
DDF can autoload external files (sounds, images, etc) if the DDF parameters are set to do such a thing.
If you use -DDF, you can autoload a set of DDF files (default doom_ddf). To load one at a time, just use the -file parameter (or alternatively, drag 'n' drop).