Valve's Left 4 Dead games are relatively straightforward "survive the zombie apocalypse as you move from A to B" shooters, but there are many subtle layers within the basic framework that this new fan film manages to nail (via Joystiq). Seriously Left 4 Dead is a short film built entirely out of fictional found footage, following three survivors as they explore the post-apocalyptic ruins on the outskirts of Savannah, Georgia.
There's a bit of a Blair Witch Project influence going on here, what with the title card nodding to the three lost survivors at the beginning and the direct address of the camera that kicks off the film. The action is staged in the Left 4 Dead style, and while the film isn't heavy on gory special effects, what's used is used very effectively. Thumbs up to YouTube poster Jason Forge and his cohorts on pulling this together.
Warning: Lots of NSFW language to be found in this video. You have been warned.