This is a good theme for a dark underground websites .Also check the header has some icons missing on the menu links.
Well if you have paid for the custom theme, then I think you should make a full use of it. Moreover the header with your site name is not visible or catchy to the naked eye, as a first impression, not a good logo. I think you should come up with some decent logo related to hacker community All the best for your efforts !!!!
The forum is nice and surely attracts more visitors.But you have to concentrate good and quality posts.