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".
Sonic Spinball
The game was developed by the American staff of Sega Technical Institute, as the Japanese staff was occupied with developing "Sonic the Hedgehog 3" and "Sonic & Knuckles". When Sega management realized that "Sonic 3" would not be completed in time for the 1993 holiday shopping season, they commissioned another "Sonic" game that would be. The game was hastily designed amid time constraints, with most work taking place over two months. "Sonic Spinball" was released for the Sega Genesis in November 1993, and for the Game Gear and Master System in 1994 and 1995, respectively.