Ninja Gaiden III: The Ancient Ship of Doom is a 1991 action-platformer which was the third and the final installment of Tecmo's Ninja Gaiden series to be released on NES. As the final part of the trilogy, Ninja Gaiden III winds up the worldwide adventures of Ryu Hayabusa, who is now framed for the murder of his girlfriend, Irene Lew. Now Ryu must prove himself innocent by finding the doppelgänger who is impersonating him. The core gameplay remained the same from the first two installments but with noticeable differences and additions. The difficulty level was also ramped up by not only making the game just more difficult, but also by changing the way continues work. In Ninja Gaiden and Ninja Gaiden II: The Dark Sword of Chaos the player had infinite continues, however in Ninja Gaiden III the player has only 5 continues to make it through the entire game. It was ported from NES to Lynx in 1993 and was released on that console in Europe as Shadow Warriors. The NES version of Ninja Gaiden III was also released via the 3DS and Wii's via Virtual Console.
The third installment in the Ninja Gaiden trilogy on NES maintained most of the gameplay features from the first two, while also making noticeable changes and differences into it like:
- Ryu's falling speed has been reduced, and upon taking damage, he is knocked back far less than in the previous games.
- Ryu's jumping mechanics have altered. He jumps over a wider arc but is more difficult to control in mid-air.
- Power-ups can now be seen inside the spherical containers, instead of being hidden until the containers were broken.
- The Vacuum Wave Art and Dragon Sword extensions were added. The Vacuum wave sends vertical blasts above and below Ryu. The Sword Extension increases the range of Ryu's attack for the duration of the level or until death.
- Ryu can now grab onto horizontal surfaces, such as pipes, vines, and the bottoms of some platforms, and climb across.
- The Ninja clone power-up was removed.
- The player is now able to climb to the top of a structure by scaling the side, then pressing the Directional pad in the direction of the top of the structure and pressing A. Previously, the player had to jump off of the side of a structure and reverse direction in mid-air to land successfully on top.
The plot of Ninja Gaiden III: The Ancient Ship of Doom explores the exploits of deadly ninja, Ryu Hayabusa who must clear his name after being framed for his girlfriend, Irene Lew's murder. As Ryu makes his way to the last known location of Irene, he finds a dubious ally in Clancy, a former associate of Foster, the director of the C.I.A. and a former acquaintance of Ryu. Apparently, Foster and Clancy were involved an experimentation, part of the "Biohazard Plan", using paranormal energies from a trans-dimensional rift created when Ryu killed The Demon within the ruins of Castle Rock Fortress. Using these energies, Foster created superhuman Bio-Noids, one of which was a doppelgänger of Ryu. So, Ryu must infiltrate the base to clear his guilt away, while fighting through hordes of difficult monsters and bosses as well as his own superhuman look-alike.