Openbox and GTK+2 theme work out-of-the-box, and will likley see few updates, if any.
GTK+3 v3.18 will see some updates, as I'm making some look and feel changes, as I port the theme to v3.20.
Also themes lightdm, kupfer, Chromium and Firefox.
If you don't care about GTK+3 v3.20, grab the 2016.03.01 release, as it supports v3.18, and will likley be more stable, until I finish porting/updating the master branch
For GTK+3, v3.18, manually move the contents of /satin/gtk-3.0/3.18 to /satin/gtk-3.0
For GTK+3, v3.20 (or later), manually move the contents of /satin/gtk-3.0/3.20 to /satin/gtk-3.0
(In the near future, we will have an install script which automates this!)
Currently, porting the GTK+3 theme to v3.20 is in process, though things look fairly good.
As this occurs, I'm updating 3.18 to match some of the more stylistic changes.