Game Informer recently had the chance to talk to Irrational Games about the company's switch back to their pre-2K buyout name. In the course of the chat, GI learned of a project that was optioned by Vivendi but scrapped after 2K's purchase -- a zombie-based first-person shooter called Division 9. Created before the zombie-shooting craze hit its peak with Left 4 Dead and Call of Duty's Nazi Zombie mode, you can watch Division 9 in all its glory on the second page of GI's article.
Division 9 was planned by Irrational after the company completed SWAT 4, but before they finished BioShock, which places the game's development around 1996 or so. GI goes into great detail about the gameplay methods (which seem to be more "stay put and survive" than Left 4 Dead's "keep moving to find salvation") in their article, which you can find here.
What do you guys think? Personally, I don't think the slow zombie approach works with FPS convention, at least when viewed through the lens of the trailer. One thing I do dig is seeing the grenade being treated as an object with actual weight, as the player is able to knock an enemy to the ground when he tosses the explosive at his chest at the 1:53 mark. Do any other FPS games do that?