Ninja is a 1986 hack n' slash game that was developed by Sculptured Software for various computer systems, including the Commodore 64, Amiga, ZX Spectrum, and DOS. You play as a ninja whose task is to break into a heavily guarded Japanese castle and steal seven idols. The castle is filled with numerous karate-ka and hired ninjas that attack on sight, but stealth is not an option in this game and you have to fight through them to get the idols. And there appears to be more to the idols as a demon called Akuma is said to reside in the castle.
In this run, eien86 plays the Commodore 64 version and exploits the wonky programming to go out of bounds and skip a couple floors to retrieve all the idols and get to Akuma as fast as possible. As it turns out, being killed by Akuma is enough for the game to declare the player as the "winner".