Kishi Densetsu

Button codes
Each of these button codes are entered at the title screen.

Both A + B + C + Start + Up and A + B + C + Start + Down show production credits, however the credits they show are different. With A + B + C + Start + Up, you get a list of full names ending with the company names. With A + B + C + Start + Down, you get a list of first initials and last names, with pictures of each person to the side of each name. Which screen is used when you beat the game is unknown.

A + B + C + Start + Right also does something; exactly what is unknown.