I spent childhood in a small town Shklov, Belarussia, where Internet became freely accessible just few years ago. People living there got used to ask their questions from the tiny local newspaper Udarny Front, which publish from time to time a column called "Questions from Readers".
Journalists working in the newspaper are taking care to answer these questions as good as they can, sometimes polling experts in the specific field. I think that this simple process still works, so in case you need something to know, you just post a question to a newspaper and then wait for a couple weeks to get an answer.
Not having anything new in gameplay was the point. Doom 3 was an old-school shooter, you with a huge arsenal of weapons vs. hordes of monstrosities from hell. And that was with amazing graphics. Doom 3 might have had really low resolution textures, but I think the lighting and shadowing remained unrivaled for years.
Though Doom3 did have a minor novelty I wish more games adapted. It had a really nice way of interacting with in-game monitors and computers, and I can't remember if any other games have done the same. Certainly not many, if there are any at all.