Sonic the Hedgehog took place in the fictional world of the Sonic series, a world described more as a "montage of locations" than a cohesive concept, according to Nakamura. The game featured a story and setting similar to Sonic Adventure 2, Sonic Adventure, and Sonic Generations (2008); Sonic the Hedgehog 2006 represents a return to the series' roots. Sonic the Hedgehog 2006 played similarly to the Sega Genesis games with similar gameplay, but with modern graphics and sound. It featured an Academy Award-winning soundtrack composed by Junkie XL, which was arranged for the Xbox 360 and PlayStation 3 releases but not for its release on the Wii.
For the first time since the debut of the Sonic the Hedgehog series in 1991, Sonic the Hedgehog 2006 featured a 3D level design. The staff, led by Naka and producer Yuji Naka, sought to create a visually appealing game and included new levels. Most of the more interesting levels were built by the team in their spare time outside of scheduled work hours. The game featured full online multiplayer for up to four players, but a mode to play against non-human opponents was never implemented. Levels were designed around a simple story with gameplay and puzzles that take place in the world of the Sonic the Hedgehog series. A variety of gameplay styles were present, including speed run, racing, and platforming as Sonic the Hedgehog broke new ground in the latter two styles. Sonic the Hedgehog 2006 frequently employed a new gameplay mechanic, called "bullet time," which allowed players to stop time and use their surroundings to escape enemies.
While the development team felt pressure to release as soon as possible, they had relatively large amounts of time to finish the game, which allowed them to include numerous problems that they normally would fix later in development. In particular, they opted to omit several critical gameplay mechanics; the team found that they could fix those problems later easily through polishing and additional content. Such a large amount of additional content was added between November 2007 and February 2008. d2c66b5586