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".
Platform game
1990 marked the release of the Super NES, along with the eagerly anticipated "Super Mario World". In order to fend off the new competition, Sega released "Sonic the Hedgehog". Whereas Nintendo's offering featured a conservative design, true to the "Mario" tradition, "Sonic" showcased a new style of design made possible by a new generation of hardware. "Sonic" featured large stages that scrolled effortlessly in all directions, as well as all manner of uneven terrain, curved hills, and a complex physics system that allowed players to rush through its levels with well-placed jumps and rolls. Lastly, there was the game's eponymous main character. Sega decided to give Sonic a rebellious personality in order to appeal to older gamers, and super speed to help show off the "Genesis"' hardware capabilities. The game proved to be a massive hit, was a successful pack-in with new systems, and cemented the view that platform games would make or break a console.