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 Gems Collection
Sonic Gems Collection is a 2005 compilation of Sega video games, primarily those in the "Sonic the Hedgehog" series. The emulated games span multiple genres and consoles—from the Sega Genesis to the Sega Saturn—and retain the features and errors of their initial releases with minimal edits. Player progress is rewarded with demos of other "Sonic" games, videos, and promotional artwork spanning the history of the "Sonic" franchise. While its 2002 predecessor, "Sonic Mega Collection", comprised the more popular "Sonic" games, "Gems Collection" focuses on more obscure games, such as "Sonic CD" and "Sonic the Fighters". Other non-"Sonic" games are included, but some, such as the "Streets of Rage" trilogy, are omitted in the North American localization.