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 CD
Released in 1988, the Genesis (known as the Mega Drive in Europe and Japan) was Sega's entry into the fourth generation of video game consoles. In mid-1990, Sega CEO Hayao Nakayama hired Tom Kalinske as CEO of Sega of America. Kalinske developed a four-point plan for sales of the Genesis: cut the console's price, develop games for the American market with a new American team, continue aggressive advertising campaigns, and ship "Sonic the Hedgehog" with the Genesis as a pack-in game. The Japanese board of directors initially disapproved of the plan, but all four points were approved by Nakayama, who told Kalinske, "I hired you to make the decisions for Europe and the Americas, so go ahead and do it." Magazines praised "Sonic" as one of the greatest games yet made, and Sega's console finally took off as customers who had been waiting for the Super Nintendo Entertainment System (SNES) decided to purchase a Genesis instead.