After making it to the top of the tower, Ryu finds Irene, who has been captured by Ashtar. After hopping on a freight train and then battling up the mountain in which the tower lies, he is ambushed by a figure who describes himself as a tribesman of the World of Chaos, led by the Emperor of Darkness Ashtar. Robert informs Ryu that Irene Lew has been captured and that he must go to the Tower of Lahja to save her. Sturgeon is sent to find Ryu to take out Ashtar. Army Special Intelligence unit member named Robert T. The story opens in the Realm of Darkness as Ashtar, the evil lord who controlled Jaquio, is informed of Jaquio's defeat he devises a plan to rule over Earth by opening the Gate of Darkness. The story begins one year after the events of the first Ninja Gaiden game. The game maintains lasting appeal among players, with one reviewer saying that Ninja Gaiden II is 'a challenging experience the likes of which gamers in the 8-bit era lived and died for'. Overall, reviewers have said that visuals and controls of Ninja Gaiden II improved over its predecessor while maintaining a high level of difficulty for players the game was criticized for having a more generic and predictable plot. The game received positive praise in previews from Electronic Gaming Monthly and Nintendo Power and continued to receive high ratings and coverage, being nominated for several awards from Nintendo Power in 1991. Sturgeon recruits the game's main protagonist Ryu Hayabusa and tells him that he is the only person who can stop him. It is about an evil emperor named Ashtar who, after hearing of Jaquio's defeat, devises a plan to take over the world and engulf it in darkness through an evil sword called the Dark Sword of Chaos. The events in Ninja Gaiden II take place one year after the events in the first Ninja Gaiden game. It was then released for the Virtual Console North America service on Octofor the Wii and on Augfor the Nintendo 3DS. The game was later released for the Commodore Amiga and DOS-based PCs by GameTek in 1991. This is the second installment in the Ninja Gaiden trilogy for the NES and it was released in Japan on April 6, 1990, in North America in May 1990, and in Europe on October 27, 1994. Ninja Gaiden II: The Dark Sword of Chaos (also known as Shadow Warriors II in Europe) is a side-scrolling platforming video game developed and published by Tecmo for the Nintendo Entertainment System (NES). This game can be played also in a version for DOS. The following emulators are available for this game: NeptunJS (JavaScript), Nesbox (Flash), RetroGames (JS) and vNES (Java).