This is a video for gameplay of a prototype Xbox game "Sonic Extreme". (Not to be confused with Sonic Xtreme which never made it to the Saturn years ago) This is a demo which seems to be a type of 'skin' over a Tony Hawk skateboard game being used to illustrate the concept they wanted. It's rather slow (for Sonic) and was never developed outside the 'borrowed' engine. For further viewing you can see the videos below.