Katana is a fork of KDE 4 for KDE 4 fans.  KDE 4 in its last days before coming of KDE 5 became a pretty good DE.  Especially the ability to have seperate wall papers and icons on each virtual desktop.  That was lost with KDE 5.  Despite requests, that was "won't fix". Other little problems also exist with KDE 5.

For those of us who developed a desirable workflow with KDE 4 and hoped for a fork similar the the KDE 3.5 Trinity project, this might be of interest.  It seems to be slimmed down, lacking resource hog Akondi and other problematic SW, but basically is KDE 4 with security updates.

I have yet to download and try it.  I am in no way part of the Katana project.  But this seems interesting for those of us who find KDE 5's activities pretty meh.  This project seems to be about 2 years old now.