Rebellion, developer of Aliens vs. Predator, NeverDead and Sniper Elite V2, is announcing a new project next month. The studio has offered a few details about the project, including the above trailer. The trailer info offers an apt description: "Footsteps quicken in the fog. Although the lone gunman's pace is swift the growing echoes of shuffling never slacken. They come."
"One man is utterly alone amidst the chaos of war," it adds, "but there are worse things to fear than bombs and bullets here." The project will be fully revealed on Valentine's Day (appropriate!), with Rebellion promising that PC players will soon see "just what is in store for those brave enough to venture into the 'Totraum'. Heil Gotterdammerung!" A quick search reveals that totraum is German for "dead space." Gotterdammerung, meanwhile, is the German translation of Ragnarok, the end of the world.
We'd speculate further, but the logo shown at the end of the trailer pretty much seals the deal. It's the Sniper Elite V2 logo, with the "V2" replaced by an inverted pentagram. So, wild guess, it's a Sniper Elite game with zombies.