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 the Hedgehog
The first "Sonic the Hedgehog" game, released in 1991, was conceived by Sega's Sonic Team division after Sega requested a mascot character to compete with Nintendo's mascot Mario. Its success spawned many sequels and helped Sega become one of the leading video game companies during the 16-bit era of the early 1990s. The first major 3D "Sonic" game, "Sonic Adventure", was released in 1998. Spin-offs have explored other genres, including racing games such as "Sonic R" (1997) and sports games such as "Mario & Sonic at the Olympic Games" (2007).