Ninjya Kage

The game is to get to the top of a castle overrun by ninja. You start off at the bottom at the moat. You must kill 10 enemies to continue on to next level. On the way you must run backwards and forwards to kill the ninja; you can also pick up special powers which will only last a little while. Get to the top and the game repeats itself but a lot harder and even more ninja to kill.