So, I couldn't get the hi-res sprite package to work, as a package that I had found and mentioned here:
After the latest comment I decided to try and unzip the pack and then load the folder into Doomsday; the moment I did that, all the games disappear. I'm guessing it's got something to do with one of the sub folders having spaces in its name and some kind of faulty set command as there were problems with stuff not loading if it had spaces in the name before. That, and Doomsday now says it can find the paths of the games it could find just fine, a path being a folder structure, it seems that setting that folder in whatever config file screwed up the names stored there. Removing the folder from the addon folders, however, does not bring back the games; and also removing Doomsday and reinstalling does not bring back the games.
So I've been trying to figure out how to reset all of Doomsday's settings so it does everything from scratch, but I can't figure out where the config files are to delete to get Doomsday to do everything from scratch.
Also, I'll try what happens if I replace the spaces in the subfolder name with underscores, if this solves this problem and it is indeed the spaces in the folder name that is the culprit, this is definitely something that needs addressing.