This may be one of those revelations that we'll just have to wait for, as there doesn't seem to be much to learn from what we're seeing at this point. It's definitely an upcoming game announcement, and it's definitely from Sony—that much seems to be confirmed. And it's been in the works for a while, as the Youtube account that uploaded the video was created in 2006. As for the rest? Gaming Everything has the most elaborate speculation, so let's turn to them:
There's a good chance it's a zombie game, especially based on the current undead-obsessed entertainment landscape and the footage in the above teaser. It might be Until Dawn, a "more serious" zombie game that will use the PlayStation Move and that we haven't heard about in some time; it may be in development at Sony Santa Monica, or it may be Hideo Kojima's next title, which he has hinted could be a zombie game.
You can also head to the site at the end of the video, www.lastofus.com, for more teaser-y goodness. We really hope it's not a game about ants being the only creatures left on earth, but we'll probably have to wait until the VGAs to find out. Let us know what you think in the comments or on Twitter or Facebook.