Sonic the Hedgehog protagonist Sonic the Hedgehog, a blue hedgehog able to run at supersonic speeds, and recurring villain Dr. Eggman, an evil scientist whose ambition is to conquer the world. Among Sonic's many allies, the most well-known include: Miles "Tails" Prower, a twin-tailed, highly intelligent yellow fox who is Sonic's sidekick and best friend; Amy Rose, a pink hedgehog who is Sonic's self-proclaimed girlfriend and a hero in her own right; Knuckles the Echidna, a coolheaded red echidna who is the guardian of the Master Emerald; Shadow the Hedgehog, an anti-heroic doppelgänger of Sonic with a dark past; and Metal Sonic, a
Sonic the Hedgehog 3 in the game's advertisements and was also released as a single, which charted in the UK at number 55. Sega planned to release a single cartridge version of "Sonic 3" and "Sonic & Knuckles", "Sonic the Hedgehog 3 Limited Edition", but it was cancelled for unknown reasons. A prototype ROM image of this version was leaked in 2008. The game is included in the compilations "Sonic Jam" (1997) for the Sega Saturn, "Sonic & Knuckles Collection" (1997) and "Sonic & Garfield Pack" (1999) for Microsoft Windows, "Sonic Mega Collection" (2002) for the GameCube, "Sonic Mega Collection Plus" (2004) for the