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
Sega released its next console, the Sega Genesis (known as the Mega Drive outside North America), in 1988. Although it was a distant third in Japan, the Genesis found major success after the release of "Sonic the Hedgehog" in 1991 and briefly outsold its main competitor, the Super Nintendo Entertainment System, in the U.S. However, later in the decade, Sega suffered commercial failures such as the 32X, Sega Saturn, and Dreamcast consoles. In 2001, Sega stopped manufacturing consoles to become a third-party developer and publisher, and was acquired by Sammy Corporation in 2004. In the years since the acquisition, Sega has been more profitable, but has been criticized for prioritizing quantity of game releases over quality.