The link for DarkXL (the listed mod for Dark Forces), while still technically valid (it is not broken, more like outdated), has realistically changed:
The old links are:
http://www.darkxl.df-21.net/screenshots.html
http://www.darkxl.df-21.net/downloads.html
They should be replaced by:
http://xlengine.com/ (Index of new site)
http://xlengine.com/?page_id=50 (Download section for latest version of DarkXL)
There doesn't appear to be an equivalent of a screenshots page on the new site although various screenshots are located throughout the website.
There are also three other games that will use the "XL Engine" although it doesn't appear that they are finished yet so I am not certain if you want to add them: Outlaws, Daggerfall & Blood.