Ninja Gaiden, released in Japan as Ninja Ryūkenden and as Shadow Warriors in Europe, is an action-platform video game developed and published by Tecmo for the Nintendo Entertainment System. Its development and release coincided with the beat 'em up arcade version of the same name. It was released in December 1988 in Japan, in March 1989 in North America, and in August 1991 in Europe. It has been ported to several other platforms, including the PC Engine, the Super NES, and mobile phones.

Retrofuturism is a movement in the creative arts showing the influence of depictions of the future produced in an earlier era. If futurism is sometimes called a "science" bent on anticipating what will come, retrofuturism is the remembering of that anticipation. Characterized by a blend of old-fashioned "retro styles" with futuristic technology, retrofuturism explores the themes of tension between past and future, and between the alienating and empowering effects of technology. Primarily reflected in artistic creations and modified technologies that realize the imagined artifacts of its parallel reality, retrofuturism can be seen as "an animating perspective on the world".