I am not an expert but i will doe next:
1, Try to find how to set up permalinks - it is something that looks like this. forumname.com/this-is-permalniks
2. Open a lot of potential good names for topic
3. Hire some one to post constantly new contact to google see there is activity.
4. and at the end of the day you need forum posters and not so seo exposure.
The first thing that impresses in a forum is how active it is. You want to show newcomers that there is a good community, which is engaging all the time. Its pointless to put effort into advertizing, before you have a stable user base. So make yourself heard - contact other gaming forums and invite the users there to check out your forum. Contact gaming communities, gaming developers, everything relevant to the topics you plan to have there.
Once having the members, you can turn your attention to SEO. Build partnerships with the forementioned forums, blogs, communities, exchange links with them and keep the relevancy. It doesn't matter if you build 5 or 50 links, as long as you remember that. Your linking buddies are a sign for search engines and the more authoritative they are - the better for you and your ranks.
Try to engage your users, post quality content, keep your posts useful and interesting, you can even think of some games with prices, for example a discount on a popular game. Within the gaming community at least you have plenty of options that will interact with your overall target group and make it interesting.
A thing that I liked in a couple of forums is that they give you a small monetary award for each quality post, in the range of $0.05 - $0.20 and reward other members that help with useful advice. Contests are also pretty hip, let's say who will get a high score on a certain game for a certain period of time...
Use your Social Media. All social channels bring different value to your brand and popularity but ALL of them are useful in their own way.
These are some useful tips. I will make sure I get on with them ASAP and will start with the permalinks.
That was a really detailed overview of the do's and don'ts in forumboard SEO optimization. It gave me some food for thought. I definitely have to focus more on bringing new members to the forum. I think contests could also turn out great or summing up the weekly discounts around PSN, XboxLive, Steam etc.