Doom III was playable. The demo shown inside the booth was actual in-game footage, not a tech demo. I know that id let either GameSpy staff and/or IDSA staff (the people who give out the E3 awards) sit down at a computer in the back of the booth and actually play the game, to show that it was the game itself, in playable form, and not a tech demo. I believe that's why Doom III was eligible for the award in the first place.