What Colour Is It? OS X Screensaver
A Mac screensaver of this website: http://whatcolourisit.scn9a.org/
Who's this by?
Original idea and website by J.E.Murphy
Screensaver by Jonic Linley
This was built on Yosemite and has been confirmed as working on El Capitan - no guarantees it will work on your Mac! If it doesn't, then there's the source code so you can fix it!