 Its initial concept had nothing in common with the original "Ninja Gaiden" series that was released for the NES.However, for retail reasons Tecmo wanted to retain a link with the previous games, which had many adherents in the West, so Itagaki was asked to rethink his ideas to target the foreign market.Analysing the earlier games, he concluded that their violence appealed to players, and included gory content, such as beheadings, in the Xbox game to retain that spirit.