The idea for Shadow originated during the development of the original Sonic Adventure in 1998, with Iizuka and Maekawa ensuring he would be a subtle, “cool” character players could care about. His design was influenced by films such as Underworld, Constantine, and Terminator. Although Shadow is one of the series’ most popular characters and was named one of the greatest video game characters by Guinness World Records in 2011, he has proven divisive among video game journalists. Some have praised his role in Sonic Adventure 2 and his levels’ preservation of the Sonic theme, but others have mocked his dark characterization. Additionally, the Shadow game received generally unfavorable reviews despite strong sales.