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 Adventure
During the early 1990s, Sega was one of the most successful video game companies due to its Genesis console. Sales for the console were driven by the popularity of its flagship franchise of 2D platformers, "Sonic the Hedgehog". During this time, series co-creator Yuji Naka worked with Sega Technical Institute (STI) in the United States to develop "Sonic" games. After the completion of "Sonic & Knuckles" in 1994, Naka moved to work with Sonic Team in Japan. STI began developing "Sonic X-treme" for the Sega Saturn"," which would have been the first "Sonic the Hedgehog" game to feature full 3D gameplay. "X-treme" suffered a series of setbacks and was canceled in 1997. The cancellation is an important factor in the Saturn's commercial failure; without it, the system had no original "Sonic" platformer. Meanwhile, Naka and Sonic Team developed original Saturn games, such as "Nights into Dreams." Due to the series' relative lack of presence on the Saturn, according to "Retro Gamer", "[b]y mid-1997 Sonic had essentially been shuffled into the background... it was astonishing to see that just six years after his debut, Sonic was already retro."