Make a Powerpoint Presentation Deck Automatically Run When You Double Click on It

To make a deck automatically start playing when you double click on it, simply save it a PowerPoint Show (.ppsx or .pps) instead of a PowerPoint Presentation (.pptx or pps). For older .ppt files, you can use is to just rename the filename extension to from .ppt to .pps. Unfortunately that trick doesn't work anymore as of Powerpoint 2007 and 2010.