Gears of War and God of War. The voice-over that accompanies the video, which Eurogamer guesses belongs a developer, explains that the game is focused on brutal, close-quarters combat.
We've contacted THQ, which holds the video game license to the Warhammer 40K universe, to see if it can shed some of the Emperor's light on this topic. While we're not exactly sure about the video's authenticity, it certainly has had some nice work put into it. Find it after the break.