Unstoppable Gorg Demo has been released for both the PC and Mac. The demo is available on Steam for both PC and Mac, and there are also standalone versions available:
http://www.unstoppablegorg.com/get/pcdemo for the PC, and
http://www.unstoppablegorg.com/get/macdemo for the mac.
The demo consists of 4 levels from the full game (including the movies of course), corresponding challenges and Arcade mode.