When longtime Sega mascot Sonic the Hedgehog made his debut on the Dreamcast console in Sonic Adventure, gamers were stunned. Sega had not only used the game to show off the tremendous possibilities of the then-new hardware, but they had reinvigorated the platform-style arcade adventure genre with massive, intricate levels, gleefully distracting minigames, and even a new kind of virtual pet, called a Chao, that could be combined with other pets, traded with friends, and even exchanged over the Internet. So...