Apparently, players have been demanding that the DOOM demo be extended because today on Twitter, @DOOM revealed that it would be continuing for a while longer. The original demo was meant to be available for the E3 conference week, however, the DOOM developers figured 'what the hell' according to their social media.
— DOOM (@DOOM) June 20, 2016
The DOOM demo is available right now for download and lets you play the opening level of the single-player campaign. Download it for free for Xbox One, Playstation 4, or PC.