If you own a Sega Genesis (aka Mega Drive), this is a game you must have!
Shinobi has a really good gameplay, combined with the need of quick moves from the player, in order to avoid enemy's shurikens, bullets and many other weapons included in this game.
The story is not to long, as you can realize if you wait a few seconds in the "Press Start To Begin" screen, altough it's a nice story, based on Joe Musashi's (principal caracter) fight to revenge his master's murder, and rescue Joe's girlfriend.
It has two different endings (or you are able to save your girlfriend, or she dies), depending the performance shown agains't the final boss - you must be really quick killing the big boos, if you want to save the girl).
Although this game has neraly 18 years (omg), i still play it sometimes, and only recently I was able to see the good ending =)
The strange thing is that I finished the game in a mobile genesis emulator (lol), right on my cell phone! I never thought as a kid that I'd finish that game on a cellphone (at that time, I guess I was neither expecting to get one, as they were so rare...).
This game is awsome, and I honestly recomend it to anyone who wants to have a real good time, either you like retro games or you don't.