You can do several things with those VALUABLE emails!!
Remember the saying "It's all in the list!"
First thing I would do is make sure you have a good auto responder set up. If you have a list of emails in the gaming niche, then you may want to conduct a survey or two to try and gauge the interest of the targeted person. Find out if they prefer console games, iPad games, etc. You can read up on how to conduct email surveys successfully by Googling it or searching this forum.
Once you have narrowed your list into categories, then you can try and create email campaigns directed to those. If they haven't opted in to anything yet and you just have a scraped email list, then the survey is a good way to capture them for your email chain. Send them offers on game guides, free gaming newsletters, or even game download sites such as Big Fish Games or something like that.
Just as with any email list, you don't want to spam. Try and engage them with value and get them to sign up for something - free newsletters or a free membership to an online gaming community. If you don't already have a website for gaming, then get to work creating one. The gaming market is huge and grows every year. With the surge in portable gaming devices, smartphones, and tablets, there is no end in sight! Study the market and its trends. Invest some time and money into carefully planning your strategy and take action.
Good luck to you on this venture!