First You need to get that music thingy with the flute. Then you go to the room where the goal is, and right before you walk like five steps look at the left side and you wil find a rock thing go...
Nintendo Gamecube game. With Sonic, Knuckles, and Tails in the "HERO" side and Eggman/Robotnik, Rouge, and Shadow in the "DARK" side. You can also enter the "Chao World" to visit your chao. For more...
In the US you can check your local Gamestop or EBGames. However, since it is a pretty old game, you might not find it in a video game store. So you should try searching for it on eBay or Amazon and...