That's Redditor silverlight using a combination of blank playmat and a video projector to make the ultimate tabletop gameplay experience!
A yoga studio in Brooklyn is allowing you to do just that, combining Dungeons and Dragons with yoga for a unique adventure which is apparently so popular some are struggling to get in:
D&d yoga. It was so crowded i couldn't get a mat or dice. pic.twitter.com/qTAHDTpanx— Ana Hurka-Robles (@AHR) January 25, 2014