As a response, Whitehead produced a proof-of-concept video showing Sega's 1993 Sega CD game Sonic CD running on an iPhone. In 2009, Sega asked fans for ideas on a game to port to iOS.
Retro Sonic later merged with two other Sonic fangames, Sonic XG and Sonic Nexus, to form Retro Sonic Nexus. The game became notable after its release for its accuracy to the games, despite not being a ROM hack or modification to an existing Sonic game. Australian programmer Christian Whitehead created the Retro Engine for use with a 2007 fangame entitled Retro Sonic, which is based upon the original Sonic games released for the Sega Genesis.
