Why in the heck do you have each part of that site on a separate subdomain?
Keep them on one website, if google likes part of the site - it'll like the rest of it.
Once google jumps into your main site and indexes it, it'll follow the links and index the rest of the pages.
A link to
xbox360.ukreleasedates.com/
and
www.xbox360.ukreleasedates.com/
Are not considered the same by google, you need to get all your Google Juice flowing to the same pages - make sure you're linking to the right page, make sure others are linking to the same page as you and not an index.asp/php/html page
Sitemaps aren't
that effective but they do help a little - signing up to webmaster tools will let you cusomtise how frequently google will crawl and index your pages, but from experience it doesn't always listen.
A down point for your site is that you're extremely link heavy, and of those links you've got
RSS link (internal), Sitemap link (internal), Related sites (external), Bookmark (external), Digg (external), All Game Info (external) and Google Ads (external).
To be honest, I'd be worried about Google thinking that it's a spam site with the amount of external links on there and only two pages on your domain being linked to.
The amount of time the Googlebot would spend on your page is minimal at best, before being whisked away to Wiki or some other website.
If joe bloggs was to find your site, and go "Oh... they've got when UT3 may be released, and a page of information about it..." *click* "I'll bookmark this... and link to it..."
They've just linked to Wiki, rather than you! Why not put all the games info on your site, you'll get more links, more chances to come up in google, more visits and potentially more clicks on your Google Ads so in theory more money
