Check this out:
Click on "All Categories". Go to "General Discussion:, and click on "Top". Be sure it's on "This Year" mode. See all those Map Game threads with over one thousand posts? Yeah.
Click on the big search icon (Second from the little speech bubble) and search "Map Game". There'll be at least six topics.
There's also an uber secret map game which may or may not exist, which you may or not be invited to.