Synchronicities & easter eggs which may appear in the1988 TECMO arcade game Ninja Gaiden:
- The bosses at the end of Round 2 (New York City stage) are a fearsome duo called the DORO Warriors.
- The theme music here is obviously a variation on rock group Black Sabbath's 1970 song "IRON MAN".
- Interestingly, game artist, writer and director Masato Kato worked on the NES / Famicom trilogy adaptations of Ninja Gaiden. He Later worked for Square on RPG Chrono Trigger. A boss character in this is the henchman Ozzie. Black Sabbath Ozzy Osbourne did the vocals for the IRON MAN song.
- The year 1999 is the setting for Ninja Gaiden which uses the prophecies of French seer Nostradamus as a story basis. Chrono Trigger also shows 1999 as being where apocalyptic "Day Of Lavos" occurs, where the main game enemy burrows up from beneath the planet's surface.
- These fighters may have been inspired by the real world wrestling duo The Road Warriors (HAWK & ANIMAL aka The Legion Doom). They sparred with the AMA between 1984-1986 and also used Sabbath's "IRON MAN as their intro.
- The game music appears on the OST as Track 7 "I AM MAN".
- The Sabbath song was featured as the theme to Marvel's 2008 IRON MAN movie (based on the comic book).
- The Road Warriors were shown in a major ad campaign for the release of
WCW Wrestling (a.k.a. World Championship Wrestling) for the Nintendo Entertainment System in 1990. The full page ads were shown on the back covers of many comic book titles at the time.
