Sonic." Thus, development of Sonic the Hedgehog began in late 2004. Sonic Team used the same title as the original 1991 Sonic the Hedgehog to indicate that it would be a major advance from the previous games and a reboot that returned to the series' roots. The Havok physics engine, previously used in their PlayStation 2 game Astro Boy (2004), allowed Sonic Team to create expansive levels previously impossible on earlier sixth-generation consoles and experiment with multiple play-styles. In addition, the engine also enabled Sonic Team to experiment with aspects such as global illumination, a night-and-day system, and giving Sonic new abilities like using ropes to leap into the air. Director Shun Nakamura demonstrated the engine during their stage shows at the Tokyo Game Show (TGS) in 2005. As the hardware of the Xbox 360 and PlayStation 3 was more powerful compared to the prior generation's consoles, the design team was able to create a more realistic setting than those of previous Sonic games. Sonic and Doctor Eggman were redesigned to better suit this updated environment: Sonic was made taller, with longer quills, and Eggman was made slimmer and given a more realistic appearance. Nakamura and producer Masahiro Kumono reasoned this was because the characters would be interacting with more humans, and felt it would make the game more appealing to older players. At one point, Sonic Team considered giving Sonic realistic fur and rubber textures. While Sonic Team had a major focus on the visuals, they considered their primary challenge creating a game that was as appealing as the original Sega Genesis Sonic games. They felt Sonic Heroes (2003) and Shadow the Hedgehog (2005) had veered into different directions and wanted to return the series to its speed-based roots in new ways. For example, they wanted to include multiple paths in levels, like the Genesis games had, a goal the realistic environments helped achieve. Sonic Team sought to "aggressively" address problems with the virtual camera system from earlier Sonic games, about which they had received many complaints. Silver the Hedgehog's gameplay style was born out of Sonic Team's desire to take advantage of Havok's realistic physics capabilities. The first design concept for Silver's character was an orange mink; he attained his final hedgehog look after over 50 design iterations. In designing Shadow's gameplay, the developers abandoned the concept of firearms previously used in Shadow the Hedgehog (2005) in favor