iScreensaver 5.2 has been released, and provides support for macOS High Sierra 10.13. Please read the 10.13 High Sierra Tech Note
as well as the Release Notes
. macOS 10.14 Mojave is under investigation, and is not yet recommended.
iScreensaver 4 Personal for Mac
For discussions specific to iScreensaver Personal 4 (available for Macs only via the Mac App Store)