[Dan Clement]

OK, here we go.

I used the GameDen theme. As a rule I'm not a big fan of "dark" styles but the light blues and greys of your style fit together very nicely, so you're looking good! I also like how it fits in with your main site theme. I think just sticking with that one theme would do you well - you don't really need four or five different ones.
You have a decent amount of forums, only a couple of which don't have anything in. It's always best to try and put at least one thread in each just so it doesn't look like your forum is dead! Nothing turns people off quicker.

Just a couple of things I'd like to mention:

The first thing I see when I bring up your forum page is a whole bunch of stats that, as a user who doesn't really know anything about the site at this stage, I'm not interested in. What I want when I visit your forum is to see what subjects are up for discussion, not who your top thread starters, best referrers and newest members are. I'd suggest moving that entire stats box to the bottom - not many people are going to look at it anyway, to be fair. If users have to scroll too far to find your content nine times out of ten they won't bother.

The green 'donate' link in the navbar is a bit difficult to read. I know you wanna draw attention to it but if people can't read it they won't bother trying. Maybe try making it red or yellow?

Forcing guests to register after viewing only one thread means you could be cutting off loads of potential members who want to get a decent picture of what your community is like before they join up. I read the one thread you linked to and then couldn't read anything else which made reviewing your actual content impossible. If you want to limit the number of threads a guest can read, set it a little higher. Maybe five or ten?

As for getting more traffic, at this stage, word of mouth is your best friend. Tell all your mates who are interested in gaming. Get them to tell all their mates. You already have a few affiliates so that's a good start. Keep forging links with similar forums and soon enough you'll have a good flow of traffic. Then consider putting your hand in your pocket and paying for Adwords.