Revenge Of The Ninja
Note: This game is also titled Ninja Haygate. 

Level skip:
Press Up, Right, Down, Down, Right, Up at the "Start Game" screen. Pause game play and press A to jump to the next level. 

Random level skip:
Complete a level, then press A + B + C to start again at a random level. 

CPU control:
Press Up, Down, Left, Down at the "Start Game" screen. The CPU will control game play. 

View all scenes:
Press Right, Left, Up, Down, Right, Left, Up at the "Start Game" screen. A "Test Mode" option will appear, allowing all game scenes to be viewed. 

Sound test:
Press Right, Down, Left, Down, Up at the "Start Game" screen.