According to Unseen64, Sonic Extreme began development without Sega’s knowledge. The prototype was developed by Vision Scape Interactive as a pitch to Sega for the Xbox, GameCube, and PlayStation 2.
In the early build, Sonic and friends would skate around on hoverboards in an open world level inspired by the iconic Green Hill Zone. Just like Tony Hawk’s Pro Skater series, Sonic Extreme focuses on performing tricks on various half-pipes and grind rails.
Vision Scape’s early work includes SeaBlade on Xbox and Tech Deck: Bare Knuckle Grind for PC. After the company was hired to work on the cutscenes in Sonic Heroes, they created a demo of Sonic Extreme using the same engine from Bare Knuckle Grind. The prototype featured three different modes. Single players could enjoy a mission mode, while two players could enjoy local multiplayer in the combat or racing modes.
While Sega declined the pitch, Sonic would finally appear on a hoverboard years later in Sonic Riders. Rather than the open world style of Sonic Extreme, Riders took on a more competitive racing design. With the obvious similarities, Vision Scape reportedly inquired about taking legal action. However, the studio had already signed a non-disclosure agreement during the development of Sonic Heroes. This meant that anything created during that time with the Sonic name legally belonged to Sega.
Sonic was last seen on a hoverboard in 2010 with the Kinect game Sonic Free Riders. However, Sega is releasing two new games in the franchise later this year. Sonic Mania harkens to the classic 2D entries while Sonic Forces blends new and old in a similar fashion to Sonic Generations.