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 2
For Sonic's 20th anniversary, Sega released "Sonic Generations", which remade aspects of various past games from the franchise. The PlayStation 3, Xbox 360, and PC versions contained a remade "Chemical Plant" level. It also contained a remake of the final boss fight, the Death Egg Robot, as the Classic Era boss of the game. Separately, the Nintendo 3DS version of the game contained a remake of the "Casino Night" level. A "Casino Night" themed pinball minigame was made available for download as a pre-order bonus for the console versions at GameStop. Remade versions of Chemical Plant and Oil Ocean also appear in the 2017 game "Sonic Mania".