"Sonic Free Riders" for the Xbox 360 is out in the USA and Canada today. (It will be released in Europe on November 10th and Japan on November 20th.)
It is the third installment in the Sonic Riders series, following Sonic Riders: Zero Gravity (which is a favourite game of mine), and it makes use of Microsoft's new "Kinect" Xbox 360 motion-sensor control peripheral. Sounds like it could be good fun to me!
