Take a look at Auto It. Not exactly a program though, but you can make standalone executable afaik -https://www.autoitscript.com/site/autoit/
This isn't exactly what you're asking for but most of the RR bros should remember this program. Good ol' AutoFire from the EQ days of playing Ranger with Bow Mastery/Headshot.
It doesn't. Unless I badly misunderstand the interface, Irfanview requires to you add files to a slideshow manually. You can't just add a directory and all subdirectories. (I've got a tree of image directories from photography projects that is ten deep in some places.) Additionally, it just creates a static file list - the slideshow does not include real-time changes to the contents of directories. You'd have to go through the whole generation process again, which is specifically what I'm trying to avoid.
I haven't checked the full documentation, but beside the hundred addons it has a lot of command line options as well. It's a few clicks to add the parent folder again and randomize them (autohotkey that or something). Hell you can even load the file list as a .txt and run a script to create that txt file.
VideoLAN - Official page for VLC media player, the Open Source video framework!
