I just wanted to post this here as the new/old version of Doom 3 has been made available. There is a lot of misinfo going around concerning the serial keys.

First, the keys are located in your Library. You must use a web browser to see them though. Go to your games library, find Doom 3, click View Downloads, More, Serial Keys. Both Doom 3 and RoE numbers will be there.

Second, you probably don't even need to look them up in the first place anyway. The offline installers automatically generate the files with the keys therein. So, the game just booted up for me without any further effort. These codes are not validated online and it has been this way since the original release.

However, if you do experience problems, there is an easy solution. Go to your installation directory (blahblahblah\DOOM 3\base) and delete doomkey and xpkey. Now, take those GOG codes and imput them both at the start of the game.

As for the online component....I couldn't say, but it seems as though you can do that without Galaxy too. I was able to see matches and whatnot available. I'm going to leave that to someone else to figure out.

You're welcome.