Ninja Gaiden, known in Japan as Ninja Ryūkenden (忍者龍剣伝, "Ninja Dragon Sword Legend") and in Europe as Shadow Warriors, is a side-scrolling beat-'em-up originally released by Tecmo as a coin-operated video game. It was first released in North America in 1988 and in Japan and Europe in 1989. The Ninja Gaiden arcade game was produced and released almost simultaneously with its home console counterpart for the NES, although they are different games with only a few similarities. Home versions of the Ninja Gaiden arcade game were released in Europe under the Shadow Warriors title in 1990 by Ocean Software for five different computer platforms (Amiga, Atari ST, Commodore 64, ZX Spectrum, and Amstrad CPC) and in North America for IBM PC by Hi-Tech Expressions. Source: Wikipedia, "Ninja Gaiden (arcade)", available under the CC-BY-SA License.