It could just be hiding?
Japanese developer Team Ninja has said that code for some entries in the Ninja Gaiden series is unable to be recovered.
Speaking to Polygon, producer Fumihiko Yasuda said that the studio was "unable to salvage" Ninja Gaiden Black and Ninja Gaiden 2 for the upcoming remaster release, Master Collection. This compilation includes the Sigma editions of the first two entries in the franchise, as well as Ninja Gaiden 3: Razor's Edge.
Ninja Gaiden Black was a reworked version of the original 2004 Ninja Gaiden reboot - with me so far? - released for the Xbox back in 2005.
"The data we have left from Ninja Gaiden Black and Ninja Gaiden 2 are in various pieces to the point that we were unable to salvage them," Yasuda said.
"However, when we worked on Sigma and Sigma 2, we went and collected as much of that data as possible and organized it. And since we could utilize this data, that’s why we chose the Sigma games. Also, the latest version of the numbered titles are the most polished, and also have a lot of additional costumes and modes, so that is why we chose these three titles."
Ninja Gaiden: Master Collection was revealed in February for PS5, PS4, Xbox Series X/S, Xbox One and PC and is slated for a June 10 release. It also apparently runs at 4K/60 frames-per-second.
This isn't the first time that code for a popular game has been damaged or lost. One high-profile case was Square Enix's Final Fantasy 8, where the original code had been misplaced. In order to get around this, developer Dotemu reverse-engineered the game and rebuilt the source code from scratch for 2019's Final Fantasy 8: Remastered.