That’s right, Ninja Gaiden Black and Ninja Gaiden II are not included. Announced in 2005, Ninja Gaiden Black was a reworked, harder version of the original 2004 game. The game was enhanced for the Xbox One X, but has been removed from Game Pass. Ninja Gaiden II was developed exclusively for the Xbox 360.
Ninja Gaiden Sigma 1 and Sigma 2 were altered PlayStation 3 re-releases, so for a “Master Collection,” many fans would prefer to play the non-Sigma games.
In the most recent Weekly Famitsu, Team Ninja brand manager Fumihiko Yasuda explains why Ninja Gaiden Black and Ninja Gaiden II were not included in the collection.
“I am aware there are pros and cons,” Yasuda said. “For me personally, Ninja Gaiden II was my debut, and so I have a deep feeling for it. But there’s another reason for this choice. To be honest, there are only fragments of the data that remain. We couldn’t salvage them. However, when developing Sigma Plus and Sigma Plus 2 [for the PlayStation Vita], we got as much of this kind of data together as we could and organised it. Because we use utilise that is the reason why we selected Sigma.”
As Kotaku reported previously, perhaps this is why it’s been up to pirates to preserve old games.