Play it here.
It seems to be a new game based off of a flash port of Doom. It even still has a few of the sounds and graphics from the original shareware Iwad. I haven't seen this discussed anywhere before, so I thought I'd share it with you guys.
Edit:Looks like they made a zombie shooter with the doom engine as well. The developer's page is filled with fps games, I wonder how many of them are using the doom engine?