So, from reading the manual, it seems the new xrick game won't work unless some additional files are installed. Fair enough, once I did that it works.
But it seems, from using RButility quite recently, that those files are not copied automatically when you tick the 'install additional game files' box on RButil's dialogue. Would it not make sense for those files to be copied along with the Doom and Quake etc files, if that box is ticked?
(It's possible this has already changed since I used RButility a few days ago)