Produced in the USA by a mixed team of Japanese and American staff, Sonic 2 had a troubled development phase that resulted in an unusually high number of abandoned concepts. However, none of that was evident when the game launched to incredible fanfare in November 1992 (Sega even went so far as to call the launch Sonic 2sday). Emphasising the strong points of the original Mega Drive classic, Sonic 2 included a greater number of stages and lifted Sonic’s speed cap considerably. It also introduced a number of recurring elements in the series, including the invincible Super Sonic, the instant acceleration Spin Dash technique and the first of Sonic’s many friends, Miles “Tails” Prower. As well as following Sonic around stages and ruining your chances of beating the special stages, the cute flying fox competed against Sonic in the split-screen multiplayer mode. Needless to say it was another smash hit and managed to sell 5 million copies in its first 60 days on sale.