Sonic Jam
"Sonic Jam" is a compilation which contains the four main "Sonic the Hedgehog" games released on the Sega Genesis: "Sonic the Hedgehog", "Sonic the Hedgehog 2", "Sonic the Hedgehog 3", and "Sonic & Knuckles". Unlike future "Sonic" collections, "Sonic Jam" does not use a Genesis emulator; the games are proper ports, and all are nearly identical to the original Sega Genesis releases, with the exception of minor bug fixes. "Sonic Jam" emulates "Sonic & Knuckles" "lock-on technology"—a special feature that allows the player to merge elements of "Sonic & Knuckles" into previous games, resulting in changes to the level design as well as the choice to play as Knuckles the Echidna in "Sonic the Hedgehog 2" and Tails in "Sonic & Knuckles".
Sega Genesis
In Japan, the Mega Drive did not fare well against its two main competitors, Nintendo's Super Famicom and NEC's PC Engine, but it achieved considerable success in North America, Brazil, and Europe. Contributing to its success were its library of arcade game ports, the popularity of Sega's "Sonic the Hedgehog" series, several popular sports franchises, and aggressive youth marketing that positioned the system as the cool console for adolescents. The release of the Super Nintendo Entertainment System two years after the Genesis resulted in a fierce battle for market share in the United States and Europe that has often been termed as a "console war" by journalists and historians. As this contest drew increasing attention to the video game industry among the general public, the Genesis and several of its highest-profile games attracted significant legal scrutiny on matters involving reverse engineering and video game violence. Controversy surrounding violent games such as "Night Trap" and "Mortal Kombat" led Sega to create the Videogame Rating Council, a predecessor to the Entertainment Software Rating Board.