The recent reveal of Ninja Gaiden 4 caused me to replay the whole series from scratch. I didn't previously get why some fans prefer Ninja Gaiden Black over its sequel, but I do now. Excellent and ...

Tecmo's Ninja Gaiden formula would see a trilogy of side-scrollers and a few handheld spin-offs, popular enough to be polished-up and rereleased as a 16-bit collection (Ninja Gaiden Trilogy).