So it's implied that the Xbox Ninja Gaiden is sort of the prequel to the NES Trilogy. In that case... mind telling why Ryu looked a bit younger in the NES Trilogy and seemingly less... hardcore than the Xbox version?
Art evolution, nothing more.
The one thing that bugs me about Ninja Gaiden 2 for the Xbox 360 is the ninja that comes flying through the door in the beginning. He looks like he's been thrown by someone. There's no one that could have thrown him. Ryu only shows up to save the girl; so it couldn't have been him. So who threw that ninja?
He was trying to bust through like the Kool-Aid Man, but Muramasa doesn't skimp on door sturdiness.
In Ninja Gaiden 3, when Ryu hears the code-name "Sea Swallow" at the beginng of Day 7, he immediately says the message is trustworthy, implying that the story takes place after the first NES game. But it doesn't look like he met Irene yet (well he did, but as Sonia) and there is some pretty blatant Ship Tease with Mizuki. So when does this game happen exactly?
In the NES original, Bloody Malth doesn't look like he has the proper physical characteristics to dress in a ninja outfit and duel Ryu's father. And why would anyone with his outfit, helmet and all, want to?
Without the helmet and outfit, he could've dressed up as a ninja and duel Ken. One can assume his physical makeover could be demonic empowerment from Jaquio.