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 Mega Collection
"Sonic Mega Collection" features twelve to fourteen complete games in one retail unit. All games are ports of their original versions on the Sega Genesis. High-resolution instruction manual scans are included for each game. Also included is an "Extras" section featuring over 100 scans of "Sonic the Hedgehog" comic covers, illustrations of "Sonic" characters throughout the franchise's history, and a handful of videos promoting other "Sonic" games, including the beginning and end sequences to "Sonic CD". In addition to the seven default games, three unlockable games are included that recreated the "Sonic & Knuckles" "lock-on technology" by allowing players access to new gameplay features and special stages by opening the hatch of the "Sonic & Knuckles" Sega Genesis cartridge and inserting another compatible cartridge, in this case each of the first three games in the "Sonic the Hedgehog" series. Also, four games published by Sega but not in the "Sonic" series could also be unlocked (two in the North American version).