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's Ultimate Genesis Collection
Sonic's Ultimate Genesis Collection (Sega Mega Drive Ultimate Collection in PAL regions) is a compilation of video games developed by Backbone Entertainment and published by Sega for PlayStation 3 and Xbox 360. The compilation features 48 Sega games (49 counting two versions of "Altered Beast") which were previously released for the Sega Genesis (including most of the "Sonic the Hedgehog" titles released for the system), arcades and the Master System. It is the sequel to the "Sega Genesis Collection" released previously for the PlayStation 2 and PlayStation Portable, however it is similar to that compilation because it contains 16 (in NTSC regions) more games (including unlockable extras).