OneCMS is an Open Source CMS also released under GPL allowing users to run there own game site easily. From the powerful template system to top-notch support, OneCMS is a great option for gaming sites.

Demo:

http://demo.opensourcecms.com/onecms/

Download:

http://www.mirrorcreator.com/files/0SUJ2ER1/OneCMS_v2.4.rar_links