With the upcoming release of Darkest of Days on September 18th, 2009, Phantom EFX has announced that a demo for the PC will be released on August 11th.
Here's some demo info:
“Custer’s infamous last stand at the Battle of Little Big Horn, and the Battle of Antietam, the bloodiest day in American history… these are just a few of humanity’s darkest days, and you can dive into both of these in the Darkest of Days demo,” said Aaron Schurman, Chief Executive Officer at Phantom EFX. “This hour-long demo lets players experience unrivaled carnage and to experience what it’s like to use futuristic weapons in period settings and see what happens when you alter history while fighting against hundreds of enemies during some of man’s greatest struggles in History!”
[update]
Update: Download the demo here:
http://www.fangaming.com/fileinfo.php?fileid=6570[/update]