Castlevania and Mega Man's soundtracks directly influenced the music of Ninja Gaiden, says series' composer

The NES has so many iconic, timeless games, and that goes for the music of those games as well. The original Ninja Gaiden trilogy has some phenomenal tunes, thanks to composers like Keiji Yamagishi. Yamagishi worked on the original trilogy, and in an interview with Eurogamer, we hear how two other seminal franchises paved the way for the sounds of Ninja Gaiden.

"When I was working on Ninja Gaiden, the producer at the time, he was a big Konami fan. He just said, go listen to Konami! But he did also suggest listening to Capcom... So two of the big influences going into it was the music of Castlevania and Mega Man."