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
Sega launched a $10 million advertising campaign for "Sonic the Hedgehog 2"s release. Sega sought a global release date to make the game available in all stores on the same day, a fairly novel concept at the time. This required Sega to reconfigure its distribution system to ensure that games were available in all major stores. The release date, Tuesday, November 24, 1992 was marketed as "Sonic 2s day". While the Genesis release in North America and the Mega Drive release in Europe both released the game on this day, Sega made the game available a few days before in Japan on November 21, 1992. 400,000 copies of "Sonic 2" were sold in the first seven days after release and over 6 million in the lifespan of the console (only 180,000 of which were in Japan).