| Electronic Gaming Monthly's September 1991 issue says the game reached stores in early June 1991, Europe around the end of June, and Japan in late July. | p. 103, "Sonic Goes Public"p. 103, "Sonic Goes Public" | Magazine |
| Electronic Gaming Monthly's September 1991 making-of says Sega's directive was an all-new game with great speed, smooth animation, and screen rotation done in software, in a 4-megabit cartridge, and that the game took a year and a half. | p. 102, "Good Games Take Time!"p. 102, "Good Games Take Time!"p. 102, "Good Games Take Time!"p. 103 | Magazine |
| Electronic Gaming Monthly's 1991 making-of says Sega of Japan chose the character through an internal sketch contest of over 100 entries, whose four finalists were a bulldog, a wolf, a man with a large moustache, and a porcupine-type animal; the moustached man became the villain, Dr. Ivo Robotnik. | p. 102, "Sonic the Wolf...???"p. 102, "Sonic the Wolf...???"p. 102, "Sonic the Wolf...???" | Magazine |
| Electronic Gaming Monthly's 1991 making-of named Minoru Kanari, manager of 16-bit consumer software development, and Naoto Ohshima, chief character designer, as the main people behind the game, with six others, and said the music was by the group Dreams Come True. | p. 102, "Do the Impossible!"p. 102, "Do the Impossible!"p. 102, "Do the Impossible!" | Magazine |
| Electronic Gaming Monthly reported in September 1991 that from that month Sonic would replace Altered Beast as the game packed in with the Genesis, and its 1992 Buyer's Guide says Sega bundled the game with the system and cut its price to $149. | p. 103 | Magazine |
| Electronic Gaming Monthly reported that Sega ran a side-by-side comparison of Sonic with "Mario 4" at the CES and similar comparisons nationwide, and that Sega officials said over 90 percent of the players preferred Sonic. | p. 103p. 103 | Magazine |
| Electronic Gaming Monthly reported in September 1991 that Sega called Sonic its best-selling cartridge in the United States. | p. 103, "Sonic Goes Public" | Magazine |