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 (1991 video game)
Sega of America CEO Tom Kalinske wanted reassurance that the character would not fail. The global head of marketing, Al Nilsen, became involved, and playtested the game across the United States with Mario fans: they were shown "Mario" and then played "Sonic the Hedgehog". 80 percent preferred "Sonic the Hedgehog", and the game was shown at the 1991 Summer Consumer Electronics Show. It was released in North America on June 23, 1991, and in the PAL regions and Japan the following month. Sega of America packaged it with American Genesis consoles, replacing "Altered Beast". This tactic enabled Sega of America to sell 15 million Genesis units. Genesis owners who bought their consoles before the switch could request free copies of "Sonic the Hedgehog" by mail. Sega of America created a large-scale marketing campaign, promoting Sonic as its mascot.